Membraneless glucose/oxygen enzymatic fuel cells using redox hydrogel films containing carbon nanotubes.

PubMed

MacAodha, Domhnall; Ó Conghaile, Peter; Egan, Brenda; Kavanagh, Paul; Leech, Dónal

2013-07-22

Co-immobilisation of three separate multiple blue copper oxygenases, a Myceliophthora thermophila laccase, a Streptomyces coelicolor laccase and a Myrothecium verrucaria bilirubin oxidase, with an [Os(2,2'-bipyridine)2 (polyvinylimidazole)10Cl](+/2+) redox polymer in the presence of multi-walled carbon nanotubes (MWCNTs) on graphite electrodes results in enzyme electrodes that produce current densities above 0.5 mA cm(-2) for oxygen reduction at an applied potential of 0 V versus Ag/AgCl. Fully enzymatic membraneless fuel cells are assembled with the oxygen-reducing enzyme electrodes connected to glucose-oxidising anodes based on co-immobilisation of glucose oxidase or a flavin adenine dinucleotide-dependent glucose dehydrogenase with an [Os(4,4'-dimethyl-2,2'-bipyridine)2(polyvinylimidazole)10Cl](+/2+) redox polymer in the presence of MWCNTs on graphite electrodes. These fuel cells can produce power densities of up to 145 μW cm(-2) on operation in pH 7.4 phosphate buffer solution at 37 °C containing 150 mM NaCl, 5 mM glucose and 0.12 mM O2. The fuel cells based on Myceliophthora thermophila laccase enzyme electrodes produce the highest power density if combined with glucose oxidase-based anodes. Although the maximum power density of a fuel cell of glucose dehydrogenase and Myceliophthora thermophila laccase enzyme electrodes decreases from 110 μW cm(-2) in buffer to 60 μW cm(-2) on testing in artificial plasma, it provides the highest power output reported to date for a fully enzymatic glucose-oxidising, oxygen-reducing fuel cell in artificial plasma. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical Glucose Biosensor Based on Glucose Oxidase Displayed on Yeast Surface.

PubMed

Wang, Hongwei; Lang, Qiaolin; Liang, Bo; Liu, Aihua

2015-01-01

The conventional enzyme-based biosensor requires chemical or physical immobilization of purified enzymes on electrode surface, which often results in loss of enzyme activity and/or fractions immobilized over time. It is also costly. A major advantage of yeast surface display is that it enables the direct utilization of whole cell catalysts with eukaryote-produced proteins being displayed on the cell surface, providing an economic alternative to traditional production of purified enzymes. Herein, we describe the details of the display of glucose oxidase (GOx) on yeast cell surface and its application in the development of electrochemical glucose sensor. In order to achieve a direct electrochemistry of GOx, the entire cell catalyst (yeast-GOx) was immobilized together with multiwalled carbon nanotubes on the electrode, which allowed sensitive and selective glucose detection.

Functionalized Anodic Aluminum Oxide Membrane–Electrode System for Enzyme Immobilization

PubMed Central

2015-01-01

A nanoporous membrane system with directed flow carrying reagents to sequentially attached enzymes to mimic nature’s enzyme complex system was demonstrated. Genetically modified glycosylation enzyme, OleD Loki variant, was immobilized onto nanometer-scale electrodes at the pore entrances/exits of anodic aluminum oxide membranes through His6-tag affinity binding. The enzyme activity was assessed in two reactions—a one-step “reverse” sugar nucleotide formation reaction (UDP-Glc) and a two-step sequential sugar nucleotide formation and sugar nucleotide-based glycosylation reaction. For the one-step reaction, enzyme specific activity of 6–20 min–1 on membrane supports was seen to be comparable to solution enzyme specific activity of 10 min–1. UDP-Glc production efficiencies as high as 98% were observed at a flow rate of 0.5 mL/min, at which the substrate residence time over the electrode length down pore entrances was matched to the enzyme activity rate. This flow geometry also prevented an unwanted secondary product hydrolysis reaction, as observed in the test homogeneous solution. Enzyme utilization increased by a factor of 280 compared to test homogeneous conditions due to the continuous flow of fresh substrate over the enzyme. To mimic enzyme complex systems, a two-step sequential reaction using OleD Loki enzyme was performed at membrane pore entrances then exits. After UDP-Glc formation at the entrance electrode, aglycon 4-methylumbelliferone was supplied at the exit face of the reactor, affording overall 80% glycosylation efficiency. The membrane platform showed the ability to be regenerated with purified enzyme as well as directly from expression crude, thus demonstrating a single-step immobilization and purification process. PMID:25025628

Modification of Glucose Oxidase biofuel cell by multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Lotfi, Ladan; Farahbakhsh, Afshin; Aghili, Sina

2018-01-01

Biofuel cells are a subset of fuel cells that employ biocatalysts. Enzyme-based biofuel cells (EBFCs) generate electrical energy from biofuels such as glucose and ethanol, which are renewable and sustainable energy sources. Glucose biofuel cells (GBFCs) are particularly interesting nowadays due to continuous harvesting of oxygen and glucose from bioavailable substrates, activity inside the human body, and environmental benign, which generate electricity through oxidation of glucose on the anode and reduction of oxygen on the cathode. Promoting the electron transfer of redox enzymes at modified electrode utilizing Nano size materials, such as carbon nanotubes (CNT), to achieve the direct electrochemistry of enzymes has been reported. The polypyrrole-MWCNTs-glucose oxidase (PY-CNT-GOx) electrode has been investigated in the present work. Cyclic voltammetry tests were performed in a three-electrode electrochemical set-up with modified electrode (Pt/PPy/MWCNTs/GOx) was used as working electrode. Platinum flat and Ag/AgCl (saturated KCl) were used as counter electrode and the reference electrode, respectively. The biofuel cells probe was prepared by immobilizing MWCNTs at the tip of a platinum (Pt) electrode (0.5 cm2) with PPy as the support matrix We have demonstrated a well-dispersed nanomaterial PPy/MWNT, which is able to immobilize GOx firmly under the condition of the absence of any other cross-linking agent.

BIOSENSOR FOR DIRECT DETERMINATION OF ORGANOPHOSPHATE NERVE AGENTS. 1. POTENTIOMETRIC ENZYME ELECTRODE. (R823663)

EPA Science Inventory

A potentiometric enzyme electrode for the direct measurement of organophosphate (OP)
nerve agents was developed. The basic element of this enzyme electrode was a pH electrode
modified with an immobilized organophosphorus hydrolase (OPH) layer formed by cross-linking
OPH ...

Disposable sensor based on enzyme-free Ni nanowire array electrode to detect glutamate.

PubMed

Jamal, Mamun; Hasan, Maksudul; Mathewson, Alan; Razeeb, Kafil M

2013-02-15

Enzyme free electrochemical sensor platform based on a vertically aligned nickel nanowire array (NiNAE) and Pt coated nickel nanowire array (Pt/NiNAE) have been developed to detect glutamate. Morphological characterisation of Ni electrodes was carried out using scanning and transmission electron microscopy combined with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the NiNAE and the Pt/NiNAE for glutamate. It has been found that both NiNAE and Pt/NiNAE electrodes showed remarkably enhanced electrocatalytic activity towards glutamate compared to planar Ni electrodes, and showed higher catalytic activity when compared to other metallic nanostructure electrodes such as gold nanowire array electrodes (AuNAE) and Pt coated gold nanowire array electrode (Pt/AuNAE). The sensitivity of NiNAE and Pt/NiNAE has been found to be 65 and 96 μA mM(-1) cm(-2), respectively, which is approximately 6 to 9 times higher than the state of the art glutamate sensor. Under optimal detection conditions, the as prepared sensors exhibited linear behaviour for glutamate detection in the concentration up to 8mM for both NiNAE and Pt/NiNAE with a limit of detection of 68 and 83 μM, respectively. Experimental results show that the vertically aligned ordered nickel nanowire array electrode (NiNAE) has significant promise for fabricating cost effective, enzyme-less, sensitive, stable and selective sensor platform. Copyright © 2012 Elsevier B.V. All rights reserved.

Electrochemical Reduction of Carbon Dioxide to Methanol by Direct Injection of Electrons into Immobilized Enzymes on a Modified Electrode.

PubMed

Schlager, Stefanie; Dumitru, Liviu Mihai; Haberbauer, Marianne; Fuchsbauer, Anita; Neugebauer, Helmut; Hiemetsberger, Daniela; Wagner, Annika; Portenkirchner, Engelbert; Sariciftci, Niyazi Serdar

2016-03-21

We present results for direct bio-electrocatalytic reduction of CO2 to C1 products using electrodes with immobilized enzymes. Enzymatic reduction reactions are well known from biological systems where CO2 is selectively reduced to formate, formaldehyde, or methanol at room temperature and ambient pressure. In the past, the use of such enzymatic reductions for CO2 was limited due to the necessity of a sacrificial co-enzyme, such as nicotinamide adenine dinucleotide (NADH), to supply electrons and the hydrogen equivalent. The method reported here in this paper operates without the co-enzyme NADH by directly injecting electrons from electrodes into immobilized enzymes. We demonstrate the immobilization of formate, formaldehyde, and alcohol dehydrogenases on one-and-the-same electrode for direct CO2 reduction. Carbon felt is used as working electrode material. An alginate-silicate hybrid gel matrix is used for the immobilization of the enzymes on the electrode. Generation of methanol is observed for the six-electron reduction with Faradaic efficiencies of around 10%. This method of immobilization of enzymes on electrodes offers the opportunity for electrochemical application of enzymatic electrodes to many reactions in which a substitution of the expensive sacrificial co-enzyme NADH is desired. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light-addressable amperometric electrodes for enzyme sensors based on direct quantum dot-electrode contacts

NASA Astrophysics Data System (ADS)

Riedel, M.; Göbel, G.; Parak, W. J.; Lisdat, F.

2014-03-01

Quantum dots allow the generation of charge carriers upon illumination. When these particles are attached to an electrode a photocurrent can be generated. This allows their use as a light-switchable layer on the surface. The QDs can not only exchange electronics with the electrode, but can also interact with donor or acceptor compounds in solution providing access to the construction of signal chains starting from an analytic molecule. The magnitude and the direction of the photocurrent depend on several factors such as electrode polarization, solution pH and composition. These defined dependencies have been evaluated with respect to the combination of QD-electrodes with enzyme reactions for sensorial purpose. CdSe/ZnS-QD-modified electrodes can be used to follow enzymatic reactions in solution based on the oxygen sensitivity. In order to develop a photoelectrochemical biosensor, e.g. glucose oxidase is immobilized on the CdSe/ZnS-electrode. One immobilization strategy applies the layer-by-layer-technique of GOD and a polyelectrolyte. Photocurrent measurements of such a sensor show a clear concentration dependent behavior. The principle of combing QD oxidase. The sensitivity of quantum dot electrodes can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be demonstrated that direct electron transfer from excited quantum dots can be achieved with the redox protein cytochrome c. This allows the detection of the protein, but also interaction partners such as a enzymes or superoxide.

Comparative study of different alcohol sensors based on Screen-Printed Carbon Electrodes.

PubMed

Costa Rama, Estefanía; Biscay, Julien; González García, María Begoña; Julio Reviejo, A; Pingarrón Carrazón, José Manuel; Costa García, Agustín

2012-05-30

Different very simple single-use alcohol enzyme sensors were developed using alcohol oxidase (AOX) from three different yeast, Hansenula sp., Pichia pastoris and Candida boidinii, and employing three different commercial mediator-based Screen-Printed Carbon Electrodes as transducers. The mediators tested, Prussian Blue, Ferrocyanide and Co-phthalocyanine were included into the ink of the working electrode. The procedure to obtain these sensors consists of the immobilization of the enzyme on the electrode surface by adsorption. For the immobilization, an AOX solution is deposited on the working electrode and left until dried (1h) at room temperature. The best results were obtained with the biosensor using Screen-Printed Co-phthalocyanine/Carbon Electrode and AOX from Hansenula sp. The reduced cobalt-phthalocyanine form is amperometrically detected at +0.4V (vs. Ag pseudo reference electrode). This sensor shows good sensitivity (1211 nA mM(-1)), high precision (2.1% RSD value for the slope value of the calibration plot) and wide linear response (0.05-1.00 mM) for ethanol determination. The sensor provides also accurate results for ethanol quantification in alcoholic drinks. Copyright © 2012 Elsevier B.V. All rights reserved.

From dynamic measurements of photosynthesis in a living plant to sunlight transformation into electricity.

PubMed

Flexer, Victoria; Mano, Nicolas

2010-02-15

We propose here a new method for the direct and continuous measurement of O(2) and glucose generated during photosynthesis. Our system is based on amperometric enzyme biosensors comprising immobilized redox enzymes (glucose oxidase (GOx) and bilirubin oxidase (BOD)) and redox hydrogels "wiring" the enzyme reaction centers to electrodes. We found that these electrodes, implanted into a living plant, responded in real time to visible light as an external stimulus triggering photosynthesis. They proved to be highly selective and fast enough and may be a valuable tool in understanding photosynthesis kinetics. Furthermore, we demonstrate that with our electrodes we could harvest glucose and O(2) produced during photosynthesis to produce energy, transforming sunlight into electricity in a simple, green, renewable, and sustainable way.

Determination of glutamine and glutamic acid in mammalian cell cultures using tetrathiafulvalene modified enzyme electrodes.

PubMed

Mulchandani, A; Bassi, A S

1996-01-01

Tetrathiafulvalene (TTF) mediated amperometric enzyme electrodes have been developed for the monitoring of L-glutamine and L-glutamic acid in growing mammalian cell cultures. The detection of glutamine was accomplished by a coupled enzyme system comprised of glutaminase plus glutamate oxidase, while the detection of glutamic acid was carried out by a single enzyme, glutamate oxidase. The appropriate enzyme(s) were immoblized on the Triton-X treated surface of tetrathiafulvalene modified carbon paste electrodes by adsorption, in conjunction with entrapment by an electrochemically deposited copolymer film of 1,3-phenylenediamine and resorcinol. Operating conditions for the glutamine enzyme electrode were optimized with respect to the amount of enzymes immoblized, pH, temperature and mobile phase flow rate for operation in a flow injection (FIA) system. When applied to glutamine and glutamic acid measurements in mammalian cell culture in FIA, the results obtained with enzyme electrodes were in excellent agreement with those determined by enzymatic analysis.

Amperometric Immunosensors for screening of Polycyclic Aromatic Hydrocarbons in water

NASA Astrophysics Data System (ADS)

Ahmad, A.; Paschero, A.; Moore, E.

2011-08-01

An amperometric immunosensor with low limit detection was developed for the screening of polycyclic aromatic hydrocarbons (PAHs) in water. The system was based on detecting the specific substance using an immunological reaction by measuring the chemical responses to specific antibodies. An integrated biochip with a three electrode system was fabricated. Gold was used as the working electrode with platinum was used as the counter electrode. A modified Ag/AgCl reference electrode was employed to enhance the stability of the immunosensors. Indirect competition enzyme-linked immunosorbent assay (ELISA) was carried out within the electrode using alkaline phosphatase (AP) as the labelled-enzyme. The system shows acceptable reproducibility and good stability. The immunosensor exhibited a wide linear response to PAHs. A limit of detection for this sensor was in the range of 1 to 10 ng ml-1 in aqueous sample.

Oxidative polymerization of 5-hydroxytryptamine to physically and chemically immobilize glucose oxidase for electrochemical biosensing.

PubMed

Huang, Ting; Liu, Zaichun; Li, Yunlong; Li, Yanqiu; Chao, Long; Chen, Chao; Tan, Yueming; Xie, Qingji; Yao, Shouzhuo; Wu, Yuping

2018-07-12

Poly(5-hydroxytryptamine) (poly(5-HT)) is exploited as a new and efficient enzyme-immobilization matrix for amperometric and biofuel cell (BFC)-based biosensing. A GOx-poly(5-HT)-Pd nanoparticles (PdNPs) bionanocomposite is prepared by Na 2 PdCl 4 -initiated oxidized polymerization of 5-hydroxytryptamine (5-HT) in a neutral aqueous solution containing glucose oxidase (GOx), and this bionanocomposite and then chitosan (CS) are cast-coated on a Pd-plated Au electrode to yield a CS/GOx-poly(5-HT)-PdNPs/Pd plate /Au enzyme electrode. Scanning/transmission electron microscopy, UV-vis spectrophotometry and electrochemical quartz crystal microbalance are employed for material characterization and/or process monitoring. Under optimized conditions, the amperometric response of the enzyme electrode is linear with glucose concentration from 2.0 μM to 6.66 mM with a sensitivity of 110 μA mM -1  cm -2 , a limit of detection of 0.2 μM, and excellent operation/storage stability in the first-generation biosensing mode. The sensitivity is larger than those of some conventional electrodes under identical conditions. The enzyme electrode also works well in the second-generation biosensing mode. By using the enzyme electrode as the anode for glucose oxidation and a Pd plate /Au electrode as the cathode for KMnO 4 reduction, a monopolar BFC is constructed as a self-powered biosensor, the current response of which is linear with glucose concentration from 50 μM to 34.5 mM. Experiments also show that poly(5-HT) is a physical and chemical dual-immobilization matrix of enzyme, since the abundant amino groups in poly(5-HT) can be used for chemical bonding of GOx. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrochemical biosensor based on immobilized enzymes and redox polymers

DOEpatents

Skotheim, Terje A.; Okamoto, Yoshiyuki; Hale, Paul D.

1992-01-01

The present invention relates to an electrochemical enzyme biosensor for use in liquid mixtures of components for detecting the presence of, or measuring the amount of, one or more select components. The enzyme electrode of the present invention is comprised of an enzyme, an artificial redox compound covalently bound to a flexible polymer backbone and an electron collector.

Biocompatible electrochemiluminescent biosensor for choline based on enzyme/titanate nanotubes/chitosan composite modified electrode.

PubMed

Dai, Hong; Chi, Yuwu; Wu, Xiaoping; Wang, Youmei; Wei, Mingdeng; Chen, Guonan

2010-02-15

A new biocompatible ECL biosensor based on enzyme/titanate nanotubes/chitosan composite film was developed for the determination of analytes in biological samples. In the fabrication of the new ECL biosensor, biocompatible titanate nanotubes (TNTs) and a model enzyme, i.e., choline oxidase (ChOX), were immobilized on a chitosan modified glassy carbon electrode (GCE) via electrostatic adsorption and covalent interaction, respectively. By this ECL biosensor, choline was enzymatically oxidized to hydrogen peroxide and detected by a sensitive luminol ECL system. The use of TNTs not only provided a biocompatible microenvironment for the immobilized enzyme, which resulted in an excellent stability and long lifetime of the ECL biosensor, but also exhibited great enhancement towards luminol ECL and thus led to a significant improvement in sensitivity of ECL biosensor. Satisfactory results were obtained when employing this biosensor in assaying the total choline in milk samples. The work would provide a common platform to develop various sensitive, selective and biocompatible ECL biosensors based on using enzyme/TNTs/CHIT composite films. Copyright 2009 Elsevier B.V. All rights reserved.

ORGANOPHOSPHORUS HYDROLASE-BASED AMPEROMETRIC SENSOR: MODULATION OF SENSITIVITY AND SUBSTRATE SELECTIVITY

EPA Science Inventory

The detection of organophosphate (OP) insecticides with nitrophenyl substituents is reported using an enzyme electrode composed of Organophosphorus Hydrolase (OPH) and albumin co-immobilized to a nylon net and attached to a carbon paste electrode. The mechanism for this biosen...

Toxin detection using a tyrosinase-coupled oxygen electrode.

PubMed

Smit, M H; Rechnitz, G A

1993-02-15

An enzyme-based "electrochemical canary" is described for the detection of cyanide. The sensing system imitates cyanide's site of toxicity in the mitochondria. The terminal sequence of electron transfer in aerobic respiration is mimicked by mediator coupling of tyrosinase catalysis to an electro-chemical system. An enzyme-coupled oxygen electrode is created which is sensitive to selective poisoning. Biocatalytic reduction of oxygen is promoted by electrochemically supplying tyrosinase with electrons. Thus, ferrocyanide is generated at a cathode and mediates the enzymatic reduction of oxygen to water. An enzyme-dependent reductive current can be monitored which is inhibited by cyanide in a concentration-dependent manner. Oxygen depletion in the reaction layer can be minimized by addressing enzyme activity using a potential pulsing routine. Enzyme activity is electrochemically initiated and terminated and the sensor becomes capable of continuous monitoring. Cyanide poisoning of the biological component is reversible, and it can be reused after rinsing. The resulting sensor detects cyanide based on its biological activity rather than its physical or chemical properties.

All Inkjet-Printed Amperometric Multiplexed Biosensors Based on Nanostructured Conductive Hydrogel Electrodes.

PubMed

Li, Lanlan; Pan, Lijia; Ma, Zhong; Yan, Ke; Cheng, Wen; Shi, Yi; Yu, Guihua

2018-06-13

Multiplexing, one of the main trends in biosensors, aims to detect several analytes simultaneously by integrating miniature sensors on a chip. However, precisely depositing electrode materials and selective enzymes on distinct microelectrode arrays remains an obstacle to massively produced multiplexed sensors. Here, we report on a "drop-on-demand" inkjet printing process to fabricate multiplexed biosensors based on nanostructured conductive hydrogels in which the electrode material and several kinds of enzymes were printed on the electrode arrays one by one by employing a multinozzle inkjet system. The whole inkjet printing process can be finished within three rounds of printing and only one round of alignment. For a page of sensor arrays containing 96 working electrodes, the printing process took merely ∼5 min. The multiplexed assays can detect glucose, lactate, and triglycerides in real time with good selectivity and high sensitivity, and the results in phosphate buffer solutions and calibration serum samples are comparable. The inkjet printing process exhibited advantages of high efficiency and accuracy, which opens substantial possibilities for massive fabrication of integrated multiplexed biosensors for human health monitoring.

Voltammetric enzyme sensor for urea using mercaptohydroquinone-modified gold electrode as the base transducer.

PubMed

Mizutani, F; Yabuki, S; Sato, Y

1997-01-01

A voltammetric urea-sensing electrode was prepared by combining a lipid-attached urease layer with a 2,5-dihydroxythiophenol-modified gold electrode. A self-assembled monolayer of dihydroxythiophenol was prepared on the gold surface by soaking the electrode into an ethanolic solution containing the modifier. A layer of the lipid-attached enzyme and that of acetyl cellulose overcoat were successively made on the dihydroxythiophenol-modified electrode by applying a dip-coating procedure. The addition of urea in a test solution (10 mM phosphate buffer, pH 7.0) brought about an increase of pH near the urease layer. The pH shift accompanied a negative shift of the anodic peak, which corresponded to the electro-oxidation of dihydroxyphenol moiety to form quinone, on the linear sweep voltammograms for the urease/dihydroxythiophenol electrode. The concentration of urea (0.2-5 mM) could be determined by measuring the electrode current at -0.05 V versus Ag/AgCl from the voltammogram. The electrode was applied to the determination of urea in human urine; the measurement of electrode current at such a low potential provided the urea determination without any electrochemical interference from L-ascorbic acid and uric acid.

A new amperometric enzyme electrode for alcohol determination.

PubMed

Gülce, H; Gülce, A; Kavanoz, M; Coşkun, H; Yildiz, A

2002-06-01

A new enzyme electrode for the determination of alcohols was developed by immobilizing alcohol oxidase in polvinylferrocenium matrix coated on a Pt electrode surface. The amperometric response due to the electrooxidation of enzymatically generated H(2)O(2) was measured at a constant potential of +0.70 V versus SCE. The effects of substrate, buffer and enzyme concentrations, pH and temperature on the response of the electrode were investigated. The optimum pH was found to be pH 8.0 at 30 degrees C. The steady-state current of this enzyme electrode was reproducible within +/-5.0% of the relative error. The sensitivity of the enzyme electrode decreased in the following order: methanol>ethanol>n-butanol>benzyl alcohol. The linear response was observed up to 3.7 mM for methanol, 3.0 mM for ethanol, 6.2 mM for n-butanol, and 5.2 mM for benzyl alcohol. The apparent Michaelis-Menten constant (K(Mapp)) value and the activation energy, E(a), of this immobilized enzyme system were found to be 5.78 mM and 38.07 kJ/mol for methanol, respectively.

A Dual Electrochemical Sensor Based on a Test-strip Assay for the Quantitative Determination of Albumin and Creatinine.

PubMed

Yasukawa, Tomoyuki; Kiba, Yuya; Mizutani, Fumio

2015-01-01

A dual-electrochemical sensor based on a test-strip assay with immunochemistry and enzyme reactions has been developed for the determination of albumin and creatinine. Each nitrocellulose membrane with an immobilization area of an anti-albumin antibody or three enzymes was prepared in the device with three working electrodes for measuring albumin, creatinine, and ascorbic acid, as well as an Ag/AgCl electrode used as a counter/pseudo-reference electrode. The reactions of three enzymes were initiated by flowing a solution containing creatinine to detect an oxidation current of hydrogen peroxide. A sandwich-type immunocomplex was formed by albumin and antibody labeled with glucose oxidase (GOx). Captured GOx catalyzed the reduction of Fe(CN)6(3-) to Fe(CN)6(4-), which was oxidized electrochemically to determine the captured albumin. The responses for creatinine and albumin increased with the concentrations in millimolar order and over the range 18.75 - 150 μg mL(-1), respectively. The present sensor would be a distinct demonstration for producing quantitative dual-assays for various biomolecules used for clinical diagnoses.

Real-Time Monitoring of Cellular Bioenergetics with a Multi-Analyte Screen-Printed Electrode

PubMed Central

McKenzie, Jennifer R.; Cognata, Andrew C.; Davis, Anna N.; Wikswo, John P.; Cliffel, David E.

2016-01-01

Real-time monitoring of changes to cellular bioenergetics can provide new insights into mechanisms of action for disease and toxicity. This work describes the development of a multi-analyte screen-printed electrode for the detection of analytes central to cellular bioenergetics: glucose, lactate, oxygen, and pH. Platinum screen-printed electrodes were designed in-house and printed by Pine Research Instrumentation. Electrochemical plating techniques were used to form quasi-reference and pH electrodes. A Dimatix materials inkjet printer was used to deposit enzyme and polymer films to form sensors for glucose, lactate, and oxygen. These sensors were evaluated in bulk solution and microfluidic environments, and found to behave reproducibly and possess a lifetime of up to six weeks. Linear ranges and limits of detection for enzyme-based sensors were found to have an inverse relationship with enzyme loading, and iridium oxide pH sensors were found to have super-Nernstian responses. Preliminary measurements where the sensor was enclosed within a microfluidic channel with RAW 264.7 macrophages were performed to demonstrate the sensors’ capabilities for performing real-time microphysiometry measurements. PMID:26125545

ZnO-Based Amperometric Enzyme Biosensors

PubMed Central

Zhao, Zhiwei; Lei, Wei; Zhang, Xiaobing; Wang, Baoping; Jiang, Helong

2010-01-01

Nanostructured ZnO with its unique properties could provide a suitable microenvironment for immobilization of enzymes while retaining their biological activity, and thus lead to an expanded use of this nanomaterial for the construction of electrochemical biosensors with enhanced analytical performance. ZnO-based enzyme electrochemical biosensors are summarized in several tables for an easy overview according to the target biosensing analyte (glucose, hydrogen peroxide, phenol and cholesterol), respectively. Moreover, recent developments in enzyme electrochemical biosensors based on ZnO nanomaterials are reviewed with an emphasis on the fabrications and features of ZnO, approaches for biosensor construction (e.g., modified electrodes and enzyme immobilization) and biosensor performances. PMID:22205864

Influence of disposable, concentric needle electrodes on muscle enzyme and lactate serum levels.

PubMed

Finsterer, Josef; Mittendorfer, Bettina; Neuhuber, Werner; Löscher, Wolfgang N

2002-08-01

Several studies addressed the question whether needle-EMG causes elevation of muscle enzymes [aspartate-aminotransferase, alanine-aminotransferase, lactate-dehydrogenase, creatine-phosphokinase (CPK), isoenzyme-MB, aldolase] and lactate with conflicting results. However, these studies used sterilizable needle electrodes and different protocols and methods to record EMGs and determine muscle enzymes. This study examined if muscle enzymes are elevated immediately after or 24 h following EMGs with disposable, concentric needle-electrodes, and if they are dependent on age, sex, muscle, number of investigated sites and previous CPK-elevation. In 53 subjects, 24 woman, 29 men, aged 17-88 years, muscle enzymes were determined before, immediately after and 24 h following EMG with disposable, concentric needle-electrodes. Muscle enzymes were not different before, immediately after and 24 h following the EMG. Muscle enzymes were not different between patients 60 years of age. Apart from higher CPK in men than women, muscle enzymes were not different between the genders. Apart from CPK, muscle enzymes were not different between the brachial biceps and anterior tibial muscle. Muscle enzymes were not different if 20 sites were investigated and were independent on pre-EMG CPK-levels. In conclusion this study shows that muscle enzymes do not increase immediately or 24 h following EMG with disposable, concentric needle-electrodes, irrespective of age, gender, muscle, number of investigated sites and pre-EMG CK-levels.

Strategies for an enzyme immobilization on electrodes: Structural and electrochemical characterizations

NASA Astrophysics Data System (ADS)

Ganesh, V.; Muthurasu, A.

2012-04-01

In this paper, we propose various strategies for an enzyme immobilization on electrodes (both metal and semiconductor electrodes). In general, the proposed methodology involves two critical steps viz., (1) chemical modification of substrates using functional monolayers [Langmuir - Blodgett (LB) films and/or self-assembled monolayers (SAMs)] and (2) anchoring of a target enzyme using specific chemical and physical interactions by attacking the terminal functionality of the modified films. Basically there are three ways to immobilize an enzyme on chemically modified electrodes. First method consists of an electrostatic interaction between the enzyme and terminal functional groups present within the chemically modified films. Second and third methods involve the introduction of nanomaterials followed by an enzyme immobilization using both the physical and chemical adsorption processes. As a proof of principle, in this work we demonstrate the sensing and catalytic activity of horseradish peroxidase (HRP) anchored onto SAM modified indium tin oxide (ITO) electrodes towards hydrogen peroxide (H2O2). Structural characterization of such modified electrodes is performed using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurements. The binding events and the enzymatic reactions are monitored using electrochemical techniques mainly cyclic voltammetry (CV).

Enzyme and microbial sensors for environmental monitoring

NASA Astrophysics Data System (ADS)

Wollenberger, U.; Neumann, B.; Scheller, Frieder W.

1993-03-01

Biosensors employing the biocatalyst on a different level of integration have been developed for monitoring environmental pollution. These probes range from laboratory specimen to commercial detectors applied to analyzers. This paper presents a selection of recent developments on amperometric enzyme and microbial biosensors. A monoenzymatic bulk type carbon electrode is described for biosensing organic hydroperoxides in aqueous solutions. Here, peroxidase is immobilized within the electrode body and the direct electron transfer between electrode and enzyme is measured. Both, reversible and irreversible inhibitors of acetylcholinesterase have been quantified by using a kinetically controlled acetylcholine enzyme sequence electrode. The inhibitory effect of pesticides such as butoxycarboxime, dimethoate, and trichlorfon could be quantified within 6 min in micrometers olar concentrations. Different multi-enzyme electrodes have been developed for the determination of inorganic phosphate. These sensors represent examples of sequentially acting enzymes in combination with enzymatic analyte recycling. Using this type of amplification nanomolar concentrations could be measured. A very fast responding microbial sensor for biological oxygen demand has been developed by immobilizing Trichosporon cutaneum onto an oxygen electrode. With this whole cell sensor waste water can be assayed with a sample frequency of 20 per hour and a working stability of more than 30 days.

Construction, assembling and application of a trehalase-GOD enzyme electrode system.

PubMed

Antonelli, M L; Arduini, F; Laganà, A; Moscone, D; Siliprandi, V

2009-01-01

Trehalose is a disaccharide important in foods, serving as a glucose source in many and also as an additive in the food preparation. Because of its peculiar physico-chemical properties it plays an important role as preservative in drying and deep-freezing treatments. A new biosensor for trehalose determination has been realized by means of a flow system, based on a reactor in which the trehalase enzyme catalyses its hydrolysis into two alpha,d-glucose molecules, and a GOD (glucose oxidase) amperometric biosensor is employed for the glucose determination. The optimum operative conditions have been laid out and a particular attention has been paid to the immobilization procedure of the two enzymes. The electrode used is of the SPE (screen-printed electrode) type and has been activated with the Prussian Blue (PB) and then assembled using GOD immobilized with Nafion. The reactor has been prepared with the trehalase enzyme chemically immobilized on an Immunodyne ABC membrane. As demonstration of its utility, the biosensor has been tested on a real sample of Boletus edulis mushroom.

Biofuel cells based on direct enzyme-electrode contacts using PQQ-dependent glucose dehydrogenase/bilirubin oxidase and modified carbon nanotube materials.

PubMed

Scherbahn, V; Putze, M T; Dietzel, B; Heinlein, T; Schneider, J J; Lisdat, F

2014-11-15

Two types of carbon nanotube electrodes (1) buckypaper (BP) and (2) vertically aligned carbon nanotubes (vaCNT) have been used for elaboration of glucose/O2 enzymatic fuel cells exploiting direct electron transfer. For the anode pyrroloquinoline quinone dependent glucose dehydrogenase ((PQQ)GDH) has been immobilized on [poly(3-aminobenzoic acid-co-2-methoxyaniline-5-sulfonic acid), PABMSA]-modified electrodes. For the cathode bilirubin oxidase (BOD) has been immobilized on PQQ-modified electrodes. PABMSA and PQQ act as promoter for enzyme bioelectrocatalysis. The voltammetric characterization of each electrode shows current densities in the range of 0.7-1.3 mA/cm(2). The BP-based fuel cell exhibits maximal power density of about 107 µW/cm(2) (at 490 mV). The vaCNT-based fuel cell achieves a maximal power density of 122 µW/cm(2) (at 540 mV). Even after three days and several runs of load a power density over 110 µW/cm(2) is retained with the second system (10mM glucose). Due to a better power exhibition and an enhanced stability of the vaCNT-based fuel cells they have been studied in human serum samples and a maximal power density of 41 µW/cm(2) (390 mV) can be achieved. Copyright © 2014 Elsevier B.V. All rights reserved.

A unified model for surface electrocatalysis based on observations with enzymes.

PubMed

Hexter, Suzannah V; Esterle, Thomas F; Armstrong, Fraser A

2014-06-28

Despite being so large, many enzymes are not only excellent electrocatalysts - making possible chemical transformations under almost reversible conditions - but they also facilitate our understanding of electrocatalysis by allowing complex processes to be dissected systematically. The electrocatalytic voltammograms obtained for enzymes attached to an electrode expose fundamental aspects of electrocatalysis that can be addressed in ways that are not available to conventional molecular or surface electrocatalysts. The roles of individual components, each characterisable by diffraction or spectroscopy, can be tested and optimised by genetic engineering. Importantly, unlike small-molecule electrocatalysts (RMM < 1000) that are structurally well-defined but invariably altered by being attached to a surface, the enzyme is a giant, multi-component assembly in which the active site is buried and relatively insensitive to the presence of the electrode and solvent interface. A central assertion is that for a given driving force (electrode potential) a true catalyst has no influence on the direction of the reaction; consequently, 'catalytic bias', i.e. the common observation that an enzyme or indeed any electrocatalyst operates preferentially in one direction, must arise from secondary effects beyond the elementary catalytic cycle. This Perspective highlights and extends a general model for electrocatalysis by surface-confined enzymes, and explains how two secondary effects control the bias: (i) the electrode potential at which electrons enter or leave the catalytic cycle; (ii) potential-dependent interconversions between states of the catalyst differing in catalytic activity due to changes in the composition and arrangements of atoms. The model, which is easily applied to enzymes that have been studied recently, highlights important considerations for understanding and developing surface-confined electrocatalysts.

A novel ethanol/oxygen microfluidic fuel cell with enzymes immobilized onto cantilevered porous electrodes

NASA Astrophysics Data System (ADS)

Desmaële, D.; Nguyen-Boisse, T. T.; Renaud, L.; Tingry, S.

2016-11-01

This paper introduces a novel design of membraneless microfluidic biofuel cell that incorporates three-dimensional porous electrodes containing immobilized enzymes to catalyze redox reactions occurring in the presence of ethanol/O2 co-laminar flows. In order to maximize the penetration depth of the reactants inside the porous medium, we report on the preliminary evaluation of cantilevered bioelectrodes, namely the fibrous electrodes protrude along the internal walls of the miniature electrochemical chamber. As a first proof-of-concept, we demonstrate the integration of a bioanode and a biocathode into a lamination-based microfluidic cell fabricated via rapid prototyping. With enzymes deposited into the fibrous structure of 25 mm long, 1 mm wide and 0.11 mm thick carbon paper electrodes, the volumetric power density reached 1.25 mW cm-3 at 0.43 V under a flow rate of 50 μL min-1. An advantage of the presented microfluidic biofuel cell is that it can be adapted to include a larger active electrode volume via the vertical stacking of multiple thin bioelectrodes. We therefore envision that our design would be amenable to reach the level of net power required to supply energy to a plurality of low-consumption electronic devices.

Non-invasive paper-based microfluidic device for ultra-low detection of urea through enzyme catalysis

NASA Astrophysics Data System (ADS)

Suresh, Vignesh; Qunya, Ong; Kanta, Bera Lakshmi; Yuh, Lee Yeong; Chong, Karen S. L.

2018-03-01

This work describes the design, fabrication and characterization of a paper-based microfluidic device for ultra-low detection of urea through enzyme catalysis. The microfluidic system comprises an entry port, a fluidic channel, a reaction zone and two electrodes (contacts). Wax printing was used to create fluidic channels on the surface of a chromatography paper. Pre-conceptualized designs of the fluidic channel are wax-printed on the paper substrate while the electrodes are screen-printed. The paper printed with wax is heated to cause the wax reflow along the thickness of the paper that selectively creates hydrophilic and hydrophobic zones inside the paper. Urease immobilized in the reaction zone catalyses urea into releasing ions and, thereby, generating a current flow between the electrodes. A measure of current with respect to time at a fixed potential enables the detection of urea. The methodology enabled urea concentration down to 1 pM to be detected. The significance of this work lies in the use of simple and inexpensive paper-based substrates to achieve detection of ultra-low concentrations of analytes such as urea. The process is non-invasive and employs a less cumbersome two-electrode assembly.

Evidence of short-range electron transfer of a redox enzyme on graphene oxide electrodes.

PubMed

Martins, Marccus V A; Pereira, Andressa R; Luz, Roberto A S; Iost, Rodrigo M; Crespilho, Frank N

2014-09-07

Direct electron transfer (DET) between redox enzymes and electrode surfaces is of growing interest and an important strategy in the development of biofuel cells and biosensors. Among the nanomaterials utilized at electrode/enzyme interfaces to enhance the electronic communication, graphene oxide (GO) has been identified as a highly promising candidate. It is postulated that GO layers decrease the distance between the flavin cofactor (FAD/FADH2) of the glucose oxidase enzyme (GOx) and the electrode surface, though experimental evidence concerning the distance dependence of the rate constant for heterogeneous electron-transfer (k(het)) has not yet been observed. In this work, we report the experimentally observed DET of the GOx enzyme adsorbed on flexible carbon fiber (FCF) electrodes modified with GO (FCF-GO), where the k(het) between GO and electroactive GOx has been measured at a structurally well-defined interface. The curves obtained from the Marcus theory were used to obtain k(het), by using the model proposed by Chidsey. In agreement with experimental data, this model proved to be useful to systematically probe the dependence of electron transfer rates on distance, in order to provide an empirical basis to understand the origin of interfacial DET between GO and GOx. We also demonstrate that the presence of GO at the enzyme/electrode interface diminishes the activation energy by decreasing the distance between the electrode surface and FAD/FADH2.

Amperometric determination of acetylcholine-A neurotransmitter, by chitosan/gold-coated ferric oxide nanoparticles modified gold electrode.

PubMed

Chauhan, Nidhi; Pundir, C S

2014-11-15

An amperometric acetylcholine biosensor was constructed by co-immobilizing covalently, a mixture of acetylcholinesterase (AChE) and choline oxidase (ChO) onto nanocomposite of chitosan (CHIT)/gold-coated ferric oxide nanoparticles (Fe@AuNPs) electrodeposited onto surface of a Au electrode and using it as a working electrode, Ag/AgCl as reference electrode and Pt wire as auxiliary electrode connected through potentiostat. The biosensor is based on electrochemical measurement of H2O2 generated from oxidation of choline by immobilized ChO, which in turn is produced from hydrolysis of acetylcholine by immobilized AChE. The biosensor exhibited optimum response within 3s at +0.2V, pH 7.0 and 30°C. The enzyme electrode had a linear working range of 0.005-400 µM, with a detection limit of 0.005 µM for acetylcholine. The biosensor measured plasma acetylcholine in apparently healthy and persons suffering from Alzheimer's disease. The enzyme electrode was unaffected by a number of serum substances but lost 50% of its initial activity after its 100 uses over a period of 3 months, when stored at 4°C. Copyright © 2014 Elsevier B.V. All rights reserved.

A novel alcohol dehydrogenase biosensor based on solid-state electrogenerated chemiluminescence by assembling dehydrogenase to Ru(bpy)(3)2+-Au nanoparticles aggregates.

PubMed

Zhang, Lihua; Xu, Zhiai; Sun, Xuping; Dong, Shaojun

2007-01-15

Based on electrogenerated chemiluminescence (ECL), a novel method for fabrication of alcohol dehydrogenase (ADH) biosensor by self-assembling ADH to Ru(bpy)(3)(2+)-AuNPs aggregates (Ru-AuNPs) on indium tin oxide (ITO) electrode surface has been developed. Positively charged Ru(bpy)(3)(2+) could be immobilized stably on the electrode surface with negatively charged AuNPs in the form of aggregate via electrostatic interaction. On the other hand, AuNPs are favourable candidates for the immobilization of enzymes because amine groups and cysteine residues in the enzymes are known to bind strongly with AuNPs. Moreover, AuNPs can act as tiny conduction centers to facilitate the transfer of electrons. Such biosensor combined enzymatic selectivity with the sensitivity of ECL detection for quantification of enzyme substrate, and it displayed wide linear range, high sensitivity and good stability.

Fabrication of high performance bioanode based on fruitful association of dendrimer and carbon nanotube used for design O2/glucose membrane-less biofuel cell with improved bilirubine oxidase biocathode.

PubMed

Korani, Aazam; Salimi, Abdollah

2013-12-15

In this study, the preparation of an integrated modified electrode based on the covalent attachment of glucose dehydrogenase (GDH) enzyme and safranin O to amine-derivative multiwalled carbon nanotubes (MWCNTs-NH2) modified glassy carbon (GC) electrode using G2.5-carboxylated PAMAM dendrimer (Den) as linking agent is reported. The obtained results indicated that the proposed system has effective bioelectrocatalytic activity toward glucose oxidation at 100 mV with onset potential of -130 mV (vs. Ag/AgCl). The performance of the prepared hybrid system of GC/MWCNTs-NH2/Den/GDH/Safranin as anode in a membraneless enzyme-based glucose/O2 biofuel cell is further evaluated. The biocathode in this system was composed of bilirubin oxidase (BOX) enzyme immobilized onto a bilirubin modified carbon nanotube GC electrode. Immobilized BOX onto CNTs/bilirubin not only show direct electron transfer but also it has excellent electrocatalytic activity toward oxygen reduction at a positive potential of 610 mV. The open circuit voltage of the cell was 590 mV. The maximum current density was 0.5 mA cm(-2), while maximum power density of 108 μW cm(-2) was achieved at voltage of 330 mV. The immobilized enzymes in anode and cathode are very stable and output power of the BFC is approximately constant after 12 h continues operation. Copyright © 2013 Elsevier B.V. All rights reserved.

Diazonium-functionalized horseradish peroxidase immobilized via addressable electrodeposition: direct electron transfer and electrochemical detection.

PubMed

Polsky, Ronen; Harper, Jason C; Dirk, Shawn M; Arango, Dulce C; Wheeler, David R; Brozik, Susan M

2007-01-16

A simple one-step procedure is introduced for the preparation of diazonium-enzyme adducts. The direct electrically addressable deposition of diazonium-modified enzymes is examined for electrochemical sensor applications. The deposition of diazonium-horseradish peroxidase leads to the direct electron transfer between the enzyme and electrode exhibiting a heterogeneous rate constant, ks, of 10.3 +/- 0.7 s-1 and a DeltaEp of 8 mV (v = 150 mV/s). The large ks and low DeltaEp are attributed to the intimate contact between enzyme and electrode attached by one to three phenyl molecules. Such an electrode shows high nonmediated catalytic activity toward H2O2 reduction. Future generations of arrayed electrochemical sensors and studies of direct electron transfer of enzymes can benefit from protein electrodes prepared by this method.

Preparation of AN Electrode Modified with a Thermostable Enzyme BACILLUS Subtilis COTA by Electrodeposition

NASA Astrophysics Data System (ADS)

Watanabe, Toshio; Yamada, Yohei; Motonaka, Junko; Yabutani, Tomoki; Sakuraba, Haruhiko; Yasuzawa, Mikito

In this study, electrodeposition of thermostable enzyme Bacillus subtilis CotA, which is a laccase and has a bilirubin oxidase (BOD) activity, was investigated. The electrodeposition was operated in a mixture of Bacillus subtilis CotA in the PBS (pH 8.0) and TritonX-100 under applying potential (1100 mV vs. Ag/AgCl for 5 min.). The current response was measured by linear sweep voltammetry technique (LSV). The thermostable enzyme Bacillus subtilis CotA electrodeposited electrode was compared with a mesophile BOD electrodeposited electrode. As a result, the Bacillus subtilis CotA modified electrode showed better sensitivity and long-term stability than the mesophile BOD modified electrode.

Electrochemical Glucose Sensors—Developments Using Electrostatic Assembly and Carbon Nanotubes for Biosensor Construction

PubMed Central

Harper, Alice; Anderson, Mark R.

2010-01-01

In 1962, Clark and Lyons proposed incorporating the enzyme glucose oxidase in the construction of an electrochemical sensor for glucose in blood plasma. In their application, Clark and Lyons describe an electrode in which a membrane permeable to glucose traps a small volume of solution containing the enzyme adjacent to a pH electrode, and the presence of glucose is detected by the change in the electrode potential that occurs when glucose reacts with the enzyme in this volume of solution. Although described nearly 50 years ago, this seminal development provides the general structure for constructing electrochemical glucose sensors that is still used today. Despite the maturity of the field, new developments that explore solutions to the fundamental limitations of electrochemical glucose sensors continue to emerge. Here we discuss two developments of the last 15 years; confining the enzyme and a redox mediator to a very thin molecular films at electrode surfaces by electrostatic assembly, and the use of electrodes modified by carbon nanotubes (CNTs) to leverage the electrocatalytic effect of the CNTs to reduce the oxidation overpotential of the electrode reaction or for the direct electron transport to the enzyme. PMID:22163652

Electrochemical glucose sensors--developments using electrostatic assembly and carbon nanotubes for biosensor construction.

PubMed

Harper, Alice; Anderson, Mark R

2010-01-01

In 1962, Clark and Lyons proposed incorporating the enzyme glucose oxidase in the construction of an electrochemical sensor for glucose in blood plasma. In their application, Clark and Lyons describe an electrode in which a membrane permeable to glucose traps a small volume of solution containing the enzyme adjacent to a pH electrode, and the presence of glucose is detected by the change in the electrode potential that occurs when glucose reacts with the enzyme in this volume of solution. Although described nearly 50 years ago, this seminal development provides the general structure for constructing electrochemical glucose sensors that is still used today. Despite the maturity of the field, new developments that explore solutions to the fundamental limitations of electrochemical glucose sensors continue to emerge. Here we discuss two developments of the last 15 years; confining the enzyme and a redox mediator to a very thin molecular films at electrode surfaces by electrostatic assembly, and the use of electrodes modified by carbon nanotubes (CNTs) to leverage the electrocatalytic effect of the CNTs to reduce the oxidation overpotential of the electrode reaction or for the direct electron transport to the enzyme.

Immobilization of polyphenol oxidase in conducting copolymers and determination of phenolic compounds in wines with enzyme electrodes.

PubMed

Kiralp, Senem; Toppare, Levent; Yağci, Yusuf

2003-11-01

Polyphenol oxidase (PPO) was immobilized in copolymers of thiophene functionalized menthyl monomer (MM) with pyrrole. Immobilization of enzyme was performed via entrapment in conducting copolymers during electrochemical polymerization of pyrrole. Maximum reaction rates, Michaelis-Menten constants and temperature, pH and operational stabilities of enzyme electrodes were investigated. Total amount of phenolic compounds in red wines of Turkey were analyzed by using these electrodes.

Picture of the Week: Hacking the bio-nano interface for better biofuels

Science.gov Websites

) influence electron transfer between the enzyme and the electrode to determine the best placement of enzymes compounds) influence electron transfer between the enzyme and the electrode to determine the best placement studied how three quinones (a class of organic compounds) influence electron transfer between the enzyme

Self-assembly of glucose oxidase on reduced graphene oxide-magnetic nanoparticles nanocomposite-based direct electrochemistry for reagentless glucose biosensor.

PubMed

Pakapongpan, Saithip; Poo-Arporn, Rungtiva P

2017-07-01

A novel approach of the immobilization of a highly selective and stable glucose biosensor based on direct electrochemistry was fabricated by a self-assembly of glucose oxidase (GOD) on reduced graphene oxide (RGO) covalently conjugated to magnetic nanoparticles (Fe 3 O 4 NPs) modified on a magnetic screen-printed electrode (MSPE). The RGO-Fe 3 O 4 nanocomposite has remarkable enhancement in large surface areas, is favorable environment for enzyme immobilization, facilitates electron transfer between enzymes and electrode surfaces and possesses superparamagnetism property. The morphology and electrochemical properties of RGO-Fe 3 O 4 /GOD were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, cyclic voltammetry (CV) and amperometry. The modified electrode was a fast, direct electron transfer with an apparent electron transfer rate constant (k s ) of 13.78s -1 . The proposed biosensor showed fast amperometric response (3s) to glucose with a wide linear range from 0.05 to 1mM, a low detection limit of 0.1μM at a signal to noise ratio of 3 (S/N=3) and good sensitivity (5.9μA/mM). The resulting biosensor has high stability, good reproducibility, excellent selectivity and successfully applied detection potential at -0.45V. This mediatorless glucose sensing used the advantages of covalent bonding and self-assembly as a new approach for immobilizing enzymes without any binder. It would be worth noting that it opens a new avenue for fabricating excellent electrochemical biosensors. This is a new approach that reporting the immobilization of glucose oxidase on reduced graphene oxide (RGO) covalently conjugated to magnetic nanoparticles (Fe 3 O 4 NPs) by electrostatic interaction and modified screen printed electrode. We propose the reagentless with fabrication method without binder and adhesive agents for immobilized enzyme. Fe 3 O 4 NPs increasing surface area to enhance the immobilization and prevent the leaching of enzymes at electrode surfaces by magnetic stickers which is improve the stability of the biosensor. Based on this synthesis technique, it is a good new strategy and simple used to fabrication of third-generation glucose biosensor and this nanocomposite could be used as a platform for disposable biosensor and biofuel cell applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Peptide nanotube-modified electrodes for enzyme-biosensor applications.

PubMed

Yemini, Miri; Reches, Meital; Gazit, Ehud; Rishpon, Judith

2005-08-15

The fabrication and notably improved performance of composite electrodes based on modified self-assembled diphenylalanine peptide nanotubes is described. Peptide nanotubes were attached to gold electrodes, and we studied the resulting electrochemical behavior using cyclic voltammetry and chronoamperometry. The peptide nanotube-based electrodes demonstrated a direct and unmediated response to hydrogen peroxide and NADH at a potential of +0.4 V (vs SCE). This biosensor enables a sensitive determination of glucose by monitoring the hydrogen peroxide produced by an enzymatic reaction between the glucose oxidase attached to the peptide nanotubes and glucose. In addition, the marked electrocatalytic activity toward NADH enabled a sensitive detection of ethanol using ethanol dehydrogenase and NAD+. The peptide nanotube-based amperometric biosensor provides a potential new tool for sensitive biosensors and biomolecular diagnostics.

Self-assembled monolayers of 1-alkenes on oxidized platinum surfaces as platforms for immobilized enzymes for biosensing

NASA Astrophysics Data System (ADS)

Alonso, Jose Maria; Bielen, Abraham A. M.; Olthuis, Wouter; Kengen, Servé W. M.; Zuilhof, Han; Franssen, Maurice C. R.

2016-10-01

Alkene-based self-assembled monolayers grafted on oxidized Pt surfaces were used as a scaffold to covalently immobilize oxidase enzymes, with the aim to develop an amperometric biosensor platform. NH2-terminated organic layers were functionalized with either aldehyde (CHO) or N-hydroxysuccinimide (NHS) ester-derived groups, to provide anchoring points for enzyme immobilization. The functionalized Pt surfaces were characterized by X-ray photoelectron spectroscopy (XPS), static water contact angle (CA), infrared reflection absorption spectroscopy (IRRAS) and atomic force microscopy (AFM). Glucose oxidase (GOX) was covalently attached to the functionalized Pt electrodes, either with or without additional glutaraldehyde crosslinking. The responses of the acquired sensors to glucose concentrations ranging from 0.5 to 100 mM were monitored by chronoamperometry. Furthermore, lactate oxidase (LOX) and human hydroxyacid oxidase (HAOX) were successfully immobilized onto the PtOx surface platform. The performance of the resulting lactate sensors was investigated for lactate concentrations ranging from 0.05 to 20 mM. The successful attachment of active enzymes (GOX, LOX and HAOX) on Pt electrodes demonstrates that covalently functionalized PtOx surfaces provide a universal platform for the development of oxidase enzyme-based sensors.

Development of Amperometric Glucose Biosensor Based on Prussian Blue Functionlized TiO2 Nanotube Arrays

PubMed Central

Gao, Zhi-Da; Qu, Yongfang; Li, Tongtong; Shrestha, Nabeen K.; Song, Yan-Yan

2014-01-01

Amperometric biosensors consisting of oxidase and peroxidase have attracted great attention because of their wide application. The current work demonstrates a novel approach to construct an enzymatic biosensor based on TiO2 nanotube arrays (TiNTs) as a supporting electrode on which Prussian Blue (PB)-an “artificial enzyme peroxidase” and enzyme glucose oxidase (GOx) have been immobilized. For this, PB nanocrystals are deposited onto the nanotube wall photocatalytically using the intrinsic photocatalytical property of TiO2, and the GOx/AuNPs nanobiocomposites are subsequently immobilized into the nanotubes via the electrodeposition of polymer. The resulting electrode exhibits a fast response, wide linear range, and good stability for glucose sensing. The sensitivity of the sensor is as high as 248 mA M−1 cm−2, and the detection limit is about 3.2 μM. These findings demonstrate a promising strategy to integrate enzymes and TiNTs, which could provide an analytical access to a large group of enzymes for bioelectrochemical applications including biosensors and biofuel cells. PMID:25367086

Inkjet-printed selective microfluidic biosensor using CNTs functionalized by cytochrome P450 enzyme

NASA Astrophysics Data System (ADS)

Krivec, Matic; Leitner, Raimund; Überall, Florian; Hochleitner, Johannes

2017-05-01

An additive manufacturing concept, consisting of 3D photopolymer printing and Ag nanoparticle printing, was investigated for the construction of a microfluidic biosensor based on immobilized cytochrome P450 enzyme. An acylate-type microfluidic chamber composed of two parts, i.e. chamber-housing and chamber-lid was printed with a polyjet 3D printer. A 3-electrode sensor structure was inkjet-printed on the lid using a combination of Ag and graphene printing. The working electrode was covered with carbon nanotubes by drop-casting and immobilized with cytochrome P450 2D6 enzyme. The microfluidic sensor shows a significant response to a test xenobiotic, i.e. dextromethorphan; the cyclic voltammetrical measurements show a corresponding oxidation peak at 0.4 V with around 5 μM detection limit.

Enzyme electrochemical sensor electrode and method of making it

DOEpatents

Rishpon, Judith; Zawodzinski, Thomas A.; Gottesfeld, Shimshon

1992-01-01

An electrochemical sensor electrode is formed from an electronic conductor coated with a casting solution containing a perfluorosulfonic acid ionomer and a selected enzyme. The selected enzyme catalyzes a reaction between a predetermined substance in a solution and oxygen to form an electrochemically active compound that is detected at the electronic conductor. The resulting perfluorosulfonic acid polymer provides a stable matrix for the enzyme for long lived enzyme activity, wherein only thin coatings are required on the metal conductor. The polymer also advantageously repels interfering substances from contacting the enzyme and contains quantities of oxygen to maintain a sensing capability during conditions of oxygen depletion in the sample. In one particular embodiment, glucose oxidase is mixed with the perfluorosulfonic acid ionomer to form an electrode for glucose detection.

Recent Advances in Polymeric Materials Used as Electron Mediators and Immobilizing Matrices in Developing Enzyme Electrodes

PubMed Central

Moyo, Mambo; Okonkwo, Jonathan O.; Agyei, Nana M.

2012-01-01

Different classes of polymeric materials such as nanomaterials, sol-gel materials, conducting polymers, functional polymers and biomaterials have been used in the design of sensors and biosensors. Various methods have been used, for example from direct adsorption, covalent bonding, crossing-linking with glutaraldehyde on composites to mixing the enzymes or use of functionalized beads for the design of sensors and biosensors using these polymeric materials in recent years. It is widely acknowledged that analytical sensing at electrodes modified with polymeric materials results in low detection limits, high sensitivities, lower applied potential, good stability, efficient electron transfer and easier immobilization of enzymes on electrodes such that sensing and biosensing of environmental pollutants is made easier. However, there are a number of challenges to be addressed in order to fulfill the applications of polymeric based polymers such as cost and shortening the long laboratory synthetic pathways involved in sensor preparation. Furthermore, the toxicological effects on flora and fauna of some of these polymeric materials have not been well studied. Given these disadvantages, efforts are now geared towards introducing low cost biomaterials that can serve as alternatives for the development of novel electrochemical sensors and biosensors. This review highlights recent contributions in the development of the electrochemical sensors and biosensors based on different polymeric material. The synergistic action of some of these polymeric materials and nanocomposites imposed when combined on electrode during sensing is discussed. PMID:22368503

Direct measurement of glutamate release in the brain using a dual enzyme-based electrochemical sensor.

PubMed

Hu, Y; Mitchell, K M; Albahadily, F N; Michaelis, E K; Wilson, G S

1994-10-03

The in vivo measurement of the rapid changes in the extracellular concentrations of L-glutamic acid in the mammalian brain during normal neuronal activity or following excessive release due to episodes of anoxia or ischemia has not been possible to this date. Current techniques for the measurement of the release of endogenous glutamate into the extracellular space of the central nervous system are relatively slow and do not measure the actual concentration of free glutamate in the extracellular space. An enzyme-based electrode with rapid response times (about 1 s) and high degree of sensitivity (less than 2 microM) and selectivity for L-glutamic acid is described in this paper. This electrode has both L-glutamate and ascorbate oxidase immobilized on its surface. The latter enzyme removes almost completely any interferences produced by the high levels of extracellular ascorbate present in brain tissue. The response of the electrode to glutamate and other potentially interfering substances was fully characterized in vitro and its selectivity, sensitivity and rapidity in responding to a rise in extracellular glutamate concentrations was also demonstrated in vivo. Placement of the electrode in the dentate gyrus of the hippocampus led to the detection of both KCl-induced release of L-glutamic acid and the release induced by stimulation of the axons in the perforant pathway. The development of this selective, sensitive and rapidly responding glutamate sensor should make it now possible to measure the dynamic events associated with glutamate neurotransmission in the central nervous system.

Biosensor for metal analysis and speciation

DOEpatents

Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

2007-01-30

A biosensor for metal analysis and speciation is disclosed. The biosensor comprises an electron carrier immobilized to a surface of an electrode and a layer of an immobilized enzyme adjacent to the electrode. The immobilized enzyme comprises an enzyme having biological activity inhibited by a metal to be detected by the biosensor.

Reticulated vitreous carbon as a scaffold for enzymatic fuel cell designing.

PubMed

Kizling, Michal; Dzwonek, Maciej; Olszewski, Bartłomiej; Bącal, Paweł; Tymecki, Łukasz; Więckowska, Agnieszka; Stolarczyk, Krzysztof; Bilewicz, Renata

2017-09-15

Three - dimensional (3D) electrodes are successfully used to overcome the limitations of the low space - time yield and low normalized space velocity obtained in electrochemical processes with two - dimensional electrodes. In this study, we developed a three - dimensional reticulated vitreous carbon - gold (RVC-Au) sponge as a scaffold for enzymatic fuel cells (EFC). The structure of gold and the real electrode surface area can be controlled by the parameters of metal electrodeposition. In particular, a 3D RVC-Au sponge provides a large accessible surface area for immobilization of enzyme and electron mediators, moreover, effective mass diffusion can also take place through the uniform macro - porous scaffold. To efficiently bind the enzyme to the electrode and enhance electron transfer parameters the gold surface was modified with ultrasmall gold nanoparticles stabilized with glutathione. These quantum sized nanoparticles exhibit specific electronic properties and also expand the working surface of the electrode. Significantly, at the steady state of power generation, the EFC device with RVC-Au electrodes provided high volumetric power density of 1.18±0.14mWcm -3 (41.3±3.8µWcm -2 ) calculated based on the volume of electrode material with OCV 0.741±0.021V. These new 3D RVC-Au electrodes showed great promise for improving the power generation of EFC devices. Copyright © 2017 Elsevier B.V. All rights reserved.

A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

PubMed

Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

2016-10-15

The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. Copyright © 2015 Elsevier B.V. All rights reserved.

Catalyzed enzyme electrodes

DOEpatents

Zawodzinski, Thomas A.; Wilson, Mahlon S.; Rishpon, Judith; Gottesfeld, Shimshon

1993-01-01

An enzyme electrode is prepared with a composite coating on an electrical conductor. The composite coating is formed from a casting solution of a perfluorosulfonic acid polymer, an enzyme, and a carbon supported catalyst. The solution may be cast directly on the conductor surface or may be formed as a membrane and applied to the surface. The perfluorosulfonic acid ionomer formed from the casting solution provides an insoluble biocompatible protective matrix for the enzyme and acts to retain the enzyme for long term availability in the electrode structure. The carbon supported catalyst provides catalytic sites throughout the layer for the oxidation of hydrogen peroxide from the enzyme reactions. The carbon support then provides a conductive path for establishing an electrical signal to the electrical conductor. In one embodiment, the electrical conductor is a carbon cloth that permits oxygen or other gas to be introduced to the perfluorosulfonic polymer to promote the enzyme reaction independent of oxygen in the solution being tested.

Electrical contacting of an assembly of pseudoazurin and nitrite reductase using DNA-directed immobilization.

PubMed

Tepper, Armand W J W

2010-05-12

A method for the electrical contacting of redox enzymes that obtain oxidizing or reducing equivalents from small electron-transfer proteins is demonstrated. The electrochemical contacting of redox enzymes through their immobilization onto electrode supports offers great potential for technological applications and for fundamental studies, but finding appropriate methods to immobilize the enzymes in an orientation allowing rapid electron transfer with the electrode has proven difficult. The copper enzyme nitrite reductase (NiR) and its natural electron-exchange partner pseudoazurin (Paz) are conjugated to a specific DNA tag and immobilized to a gold electrode into a stoichiometrically defined assembly. The DNA tethered to the electrode surface acts as flexible place-holder for the protein components, allowing both proteins to move within the construct. It is shown that Paz efficiently shuttles electrons between the electrode and the NiR enzyme, allowing the electrochemically driven NiR catalysis to be monitored. The activity of the NiR enzyme remains unperturbed by the immobilization. The rate-limiting step of the system is tentatively ascribed to the dissociation of the Paz/NiR complex. The electrochemical response of the system reports not only on the NiR catalysis and on interfacial electron transfer but also on the interaction between NiR and Paz.

Reagentless biosensor based on layer-by-layer assembly of functional multiwall carbon nanotubes and enzyme-mediator biocomposite.

PubMed

Zhou, Xing-Hua; Xi, Feng-Na; Zhang, Yi-Ming; Lin, Xian-Fu

2011-06-01

A simple and controllable layer-by-layer (LBL) assembly method was proposed for the construction of reagentless biosensors based on electrostatic interaction between functional multiwall carbon nanotubes (MWNTs) and enzyme-mediator biocomposites. The carboxylated MWNTs were wrapped with polycations poly(allylamine hydrochloride) (PAH) and the resulting PAH-MWNTs were well dispersed and positively charged. As a water-soluble dye methylene blue (MB) could mix well with horseradish peroxidase (HRP) to form a biocompatible and negatively-charged HRP-MB biocomposite. A (PAH-MWNTs/HRP-MB)(n) bionanomultilayer was then prepared by electrostatic LBL assembly of PAH-MWNTs and HRP-MB on a polyelectrolyte precursor film-modified Au electrode. Due to the excellent biocompatibility of HRP-MB biocomposite and the uniform LBL assembly, the immobilized HRP could retain its natural bioactivity and MB could efficiently shuttle electrons between HRP and the electrode. The incorporation of MWNTs in the bionanomultilayer enhanced the surface coverage concentration of the electroactive enzyme and increased the catalytic current response of the electrode. The proposed biosensor displayed a fast response (2 s) to hydrogen peroxide with a low detection limit of 2.0×10⁻⁷ mol/L (S/N=3). This work provided a versatile platform in the further development of reagentless biosensors.

Amperometric Enzyme Electrodes

DTIC Science & Technology

1989-12-01

form of carbon (glascy carbon , graphite, reticulated vitreous carbon , carbon paste, fiber or foil). Carbon is favored for enzyme immoblization...the surface for covalent bonding. The most frequently used electrode material, glassy carbon , often displays complex behavior. Although attempts have...Mixed Carbon Paste Electrode with an Immobilized Layer of D-Gluconate Dehydrogenase from Bacteral Membranes," Agric. Biol. Chelm., 51 (1987), 747-754

Development of a common biosensor format for an enzyme based biosensor array to monitor fruit quality.

PubMed

Jawaheer, Shobha; White, S F; Rughooputh, S D D V; Cullen, David C

2003-10-15

Individual enzyme-based biosensors involving three-electrode systems were developed for the detection of analytes comprising markers of the stage of maturity and quality in selected fruits of economic importance to tropical countries. Importantly, a common fabrication format has been developed to simplify manufacture and allow future integration of the individual sensors into a single multi-sensor array. Specifically, sensors for beta-D-glucose, total D-glucose, sucrose and ascorbic acid have been developed. Pectin, a natural polysaccharide present in plant cells, was used as a novel matrix to enhance enzyme entrapment and stabilisation in the sensors. Except for ascorbic acid, all the sensors function via the detection of enzymatically generated H2O2 at rhodinised carbon electrodes. Since ascorbic acid is electrochemically active at the working potential chosen (+350 mV vs. Ag/AgCl), it was measured directly. Enzyme sensors demonstrated expected response with respect to their substrates, typically 0-0.8 microA/20 mm2 electrode area response over analyte ranges of 0-7 mM. Interferences related to electrochemically active compounds present in fruits under study were significantly reduced by inclusion of a suitable cellulose acetate (CA) membrane or by enzymatic inactivation with ascorbate oxidase. Initial development was carried out into production of biosensor arrays. CA membranes were used to improve the linear range of the sensors, producing up to a fivefold improvement in the detection range compared to sensors without an additional diffusion barrier.

Electrostatic interaction between an enzyme and electrodes in the electric double layer examined in a view of direct electron transfer-type bioelectrocatalysis.

PubMed

Sugimoto, Yu; Kitazumi, Yuki; Tsujimura, Seiya; Shirai, Osamu; Yamamoto, Masahiro; Kano, Kenji

2015-01-15

Effects of the electrode poential on the activity of an adsorbed enzyme has been examined by using copper efflux oxidase (CueO) as a model enzyme and by monitoring direct electron transfer (DET)-type bioelectrocatalysis of oxygen reduction. CueO adsorbed on bare Au electrodes at around the point of zero charge (E(pzc)) shows the highest DET activity, and the activity decreases as the adsorption potential (E(ad); at which the enzyme adsorbs) is far from E(pzc). We propose a model to explain the phenomena in which the electrostatic interaction between the enzyme and electrodes in the electric double layer affects the orientation and the stability of the adsorbed enzyme. The self-assembled monolayer of butanethiol on Au electrodes decreases the electric field in the outside of the inner Helmholtz plane and drastically diminishes the E(ad) dependence of the DET activity of CueO. When CueO is adsorbed on bare Au electrodes under open circuit potential and then is held at hold potentials (E(ho)) more positive than E(pzc), the DET activity of the CueO rapidly decreases with the hold time. The strong electric field with positive surface charge density on the metallic electrode (σ(M)) leads to fatal denaturation of the adsorbed CueO. Such denaturation effect is not so serious at E(ho)

A Study in Enzyme Kinetics Using an Ion-Specific Electrode.

ERIC Educational Resources Information Center

Turchi, Sandra; And Others

1989-01-01

Describes an undergraduate biochemistry laboratory experiment on enzyme kinetics using the D-amino acid oxidase system and an ammonia electrode. Preparation of an ammonia standard curve, a sample preparation, and inhibition studies are discussed. (YP)

Glucose-oxidase label-based redox cycling for an incubation period-free electrochemical immunosensor.

PubMed

Singh, Amardeep; Park, Seonhwa; Yang, Haesik

2013-05-21

Catalytic reactions of enzyme labels in enzyme-linked immunosorbent assays require a long incubation period to obtain high signal amplification. We present herein a simple immunosensing scheme in which the incubation period is minimized without a large increase in the detection limit. This scheme is based on electrochemical-enzymatic (EN) redox cycling using glucose oxidase (GOx) as an enzyme label, Ru(NH3)6(3+) as a redox mediator, and glucose as an enzyme substrate. Fast electron mediation of Ru(NH3)6(3+) between the electrode and the GOx label attached to the electrode allows high signal amplification. The acquisition of chronocoulometric charges at a potential in the mass transfer-controlled region excludes the influence of the kinetics of Ru(NH3)6(2+) electrooxidation and also facilitates high signal-to-background ratios. The reaction between reduced GOx and Ru(NH3)6(3+) is rapid even in air-saturated Tris buffer, where the faster competitive reaction between reduced GOx and dissolved oxygen also occurs. The direct electrooxidation of glucose at the electrode and the direct electron transfer between glucose and Ru(NH3)6(3+) that undesirably increase background levels occur relatively slowly. The detection limit for the EN redox cycling-based detection of cancer antigen 125 (CA-125) in human serum is slightly higher than 0.1 U/mL for the incubation period of 0 min, and the detection limits for the incubation periods of 5 and 10 min are slightly lower than 0.1 U/mL, indicating that the detection limits are almost similar irrespective of the incubation period and that the immunosensor is highly sensitive.

Graphene-coated carbon fiber cloth for flexible electrodes of glucose fuel cells

NASA Astrophysics Data System (ADS)

Hoshi, Kazuki; Muramatsu, Kazuo; Sumi, Hisato; Nishioka, Yasushiro

2016-02-01

In this work, we fabricated flexible electrodes for a miniaturized, simple structured, and flexible glucose biofuel cell (BFC) using a graphene-coated carbon fiber cloth (GCFC). The areas of the anode and cathode electrodes were 3 × 10 mm2. The anode area was coated with the enzyme glucose oxidase, and the cathode area was coated with the enzyme bilirubin oxidase. No ion-exchange film was needed because glucose oxidase selectively oxidizes glucose and bilirubin oxidase selectively reduces oxygen. The power density of the BFC with GCFC electrodes in a phosphate buffer solution of 200 mM glucose solution at room temperature was 34.3 µW/cm2 at 0.43 V. The power density of a BFC using carbon fiber cloth (CFC) without graphene modification was 18.5 µW/cm2 at 0.13 V. The BFC with the GCFC electrode continued to function longer than 24 h with a power density higher than 5 µW/cm2. These effects were attributed to the much larger effective surface areas of the GCFC electrodes that maintain more enzymes than those of the CFC electrodes.

Biofuel cell based on direct bioelectrocatalysis.

PubMed

Ramanavicius, Arunas; Kausaite, Asta; Ramanaviciene, Almira

2005-04-15

A biofuel cell, consisting of two 3mm diameter carbon rod electrodes and operating at ambient temperature in aqueous solution, pH 6, is described. Biofuel cell based on enzymes able to exchange directly electrons with carbon electrodes was constructed and characterized. Anode of the biofuel cell was based on immobilized Quino-hemoprotein alcohol dehydrogenase from Gluconobacter sp. 33 (QH-ADH), cathode on co-immobilized glucose oxidase from Aspergilus niger (GO(x)) and microperoxidase 8 from the horse heart (MP-8) acting in the consecutive mode. Two enzymes GO(x) and MP-8 applied in the design of biofuel cell cathode were acting in consecutive mode and by hydrogen peroxide oxidized MP-8 was directly accepting electrons from carbon rod electrode. If ethanol was applied as an energy source the maximal open circuit potential of the biofuel cell was -125 mV. If glucose was applied as energy source the open circuit potential of the cell was +145 mV. The maximal open circuit potential (270 mV) was achieved in the presence of extent concentration (over 2 mM) of both substrates (ethanol and glucose). Operational half-life period (tau(1/2)) of the biofuel cell was found to be 2.5 days.

Capability of parasulfonato calix[6]arene, as an anion dopant, and organic solvents in enhancing the sensitivity and loading of glucose oxidase (GOx) on polypyrrole film in a biosensor: a comparative study.

PubMed

Safarnavadeh, Vahideh; Zare, Karim; Fakhari, Ali Reza

2013-11-15

In this study, the effects of two solvents (acetonitrile and water) and an anion dopant (para sulfonato calix[6]arene ((C[6]S)(-6))), on the manufacturing and properties of a polypyrrole (Ppy)-based, glucose oxidase amperometric biosensor were studied. Pyrrole was polymerized using galvanostatic mode in two different solvents, and the effect of (C[6]S)(-6) was studied in aqueous solution. The morphology of the obtained polypyrrole films was studied by scanning electron microscopy (SEM). Glucose oxidase (GOx) was adsorbed on the Ppy films via cross-linking method. Then the amperometric responses of the Pt/Ppy/GOx electrodes were measured using the amperometric method at the potential of 0.7 V in steps of adding a glucose solution to a potassium phosphate buffer. We found that acetonitrile and (C[6]S)(-6) increase the sensitivity of the enzyme electrode up to 79.30 µA M(-1)cm(-2) in comparison with 31.60 μA M(-1)cm(-2) for the electrode synthesized in calixarene free aqueous solvent. Also (C[6]S)(-6) has the main role in preventing leaching the enzyme from the electrode. This fact increases loading of the enzyme and stability of the biosensor. So that the steady state current density of the aforementioned electrode increases linearly with increasing glucose concentration up to 190 mM. Whereas the linearity was observed up to 61 mM and 80 mM for the electrodes made using calixarene free acetonitrile and aqueous solutions, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Application of ionic liquids in electrochemical sensing systems.

PubMed

Shiddiky, Muhammad J A; Torriero, Angel A J

2011-01-15

Since 1992, when the room temperature ionic liquids (ILs) based on the 1-alkyl-3-methylimidazolium cation were reported to provide an attractive combination of an electrochemical solvent and electrolyte, ILs have been widely used in electrodeposition, electrosynthesis, electrocatalysis, electrochemical capacitor, and lithium batteries. However, it has only been in the last few years that electrochemical biosensors based on carbon ionic liquid electrodes (CILEs) and IL-modified macrodisk electrodes have been reported. However, there are still a lot of challenges in achieving IL-based sensitive, selective, and reproducible biosensors for high speed analysis of biological and environmental compounds of interest. This review discusses the principles of operation of electrochemical biosensors based on CILEs and IL/composite-modified macrodisk electrodes. Subsequently, recent developments and major strategies for enhancing sensing performance are discussed. Key challenges and opportunities of IL-based biosensors to further development and use are considered. Emphasis is given to direct electron-transfer reaction and electrocatalysis of hemeproteins and enzyme-modified composite electrodes. Copyright © 2010 Elsevier B.V. All rights reserved.

Effective Electrochemistry of Human Sulfite Oxidase Immobilized on Quantum-Dots-Modified Indium Tin Oxide Electrode.

PubMed

Zeng, Ting; Leimkühler, Silke; Koetz, Joachim; Wollenberger, Ulla

2015-09-30

The bioelectrocatalytic sulfite oxidation by human sulfite oxidase (hSO) on indium tin oxide (ITO) is reported, which is facilitated by functionalizing of the electrode surface with polyethylenimine (PEI)-entrapped CdS nanoparticles and enzyme. hSO was assembled onto the electrode with a high surface loading of electroactive enzyme. In the presence of sulfite but without additional mediators, a high bioelectrocatalytic current was generated. Reference experiments with only PEI showed direct electron transfer and catalytic activity of hSO, but these were less pronounced. The application of the polyelectrolyte-entrapped quantum dots (QDs) on ITO electrodes provides a compatible surface for enzyme binding with promotion of electron transfer. Variations of the buffer solution conditions, e.g., ionic strength, pH, viscosity, and the effect of oxygen, were studied in order to understand intramolecular and heterogeneous electron transfer from hSO to the electrode. The results are consistent with a model derived for the enzyme by using flash photolysis in solution and spectroelectrochemistry and molecular dynamic simulations of hSO on monolayer-modified gold electrodes. Moreover, for the first time a photoelectrochemical electrode involving immobilized hSO is demonstrated where photoexcitation of the CdS/hSO-modified electrode lead to an enhanced generation of bioelectrocatalytic currents upon sulfite addition. Oxidation starts already at the redox potential of the electron transfer domain of hSO and is greatly increased by application of a small overpotential to the CdS/hSO-modified ITO.

An improved glucose/O2 membrane-less biofuel cell through glucose oxidase purification.

PubMed

Gao, Feng; Courjean, Olivier; Mano, Nicolas

2009-10-15

A key objective in any bioelectrochemical systems is to improve the current densities and mass transport limitation. Most of the work is focused on increasing the specific surface of the electrodes or improving the electron transfer between enzymes and electrodes. However, nothing is said about the comparison of purified and non-purified enzyme and their effects on the biosensor efficiency. To illustrate the effect of the enzyme purity, we studied the widely used commercial Glucose Oxidase (GOx) from Aspergillus niger that we are using in our miniature membrane-less biofuel cell. Our results indicate that even if additional compounds contained in the lyophilized enzyme powder do not interfere with its intrinsic catalytic properties, they could prevent a good electron transfer between the enzyme and the electrode surface. By introducing a purified glucose oxidase into a bioelectrocatalyst immobilized on an electrode surface, we show that we can increase the interaction between the enzyme and the redox polymer, forming a better homogenous, leather like gel. At 5mM glucose concentration and under oxygen atmosphere, the current is three-fold higher when using a purified enzyme than it is when using a non-purified enzyme. Built with this novel anode, we showed that a miniature implantable membrane-less glucose-O(2) biofuel cell could produce, under air, twice the power density that is usually obtained when using a non-purified GOx.

Polymer-based protein engineering grown ferrocene-containing redox polymers improve current generation in an enzymatic biofuel cell.

PubMed

Campbell, Alan S; Murata, Hironobu; Carmali, Sheiliza; Matyjaszewski, Krzysztof; Islam, Mohammad F; Russell, Alan J

2016-12-15

Enzymatic biofuel cells (EBFCs) are capable of generating electricity from physiologically present fuels making them promising power sources for the future of implantable devices. The potential application of such systems is limited, however, by inefficient current generation. Polymer-based protein engineering (PBPE) offers a unique method to tailor enzyme function through tunable modification of the enzyme surface with functional polymers. In this study, we report on the modification of glucose oxidase (GOX) with ferrocene-containing redox polymers to increase current generation efficiency in an enzyme-modified anode. Poly(N-(3-dimethyl(ferrocenyl)methylammonium bromide)propyl acrylamide) (pFcAc) was grown from covalently attached, water-soluble initiator molecules on the surface of GOX in a "grafting-from" approach using atom transfer radical polymerization (ATRP). The covalently-coupled ferrocene-containing polymers on the enzyme surface promoted the effective "wiring" of the GOX active site to an external electrode. The resulting GOX-pFcAc conjugates generated over an order of magnitude increase in current generation efficiency and a 4-fold increase in maximum EBFC power density (≈1.7µWcm(-2)) with similar open circuit voltage (0.27V) compared to native GOX when physically adsorbed onto paddle-shaped electrodes made up of electrospun polyacrylonitrile fibers coated with gold nanoparticles and multi-wall carbon nanotubes. The formation of electroactive enzyme-redox polymer conjugates using PBPE represents a powerful new tool for the improvement of mediated enzyme-based bioelectronics without the need for free redox mediators or anode/cathode compartmentalization. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Development of a Portable Blood Sugar Apparatus and GOD Enzyme Strip.

PubMed

Zhen-Cheng, Chen; Yu-Qian, Zhao; Jing-Tian, Tang; Ling-Yun, Li

2005-01-01

A pocket blood sugar apparatus tested by enzyme electrode, which was designed using carbon and silver plasma as conducting materials. Both the work and reference electrodes are applied to the parts of enzyme electrode. The glucose oxidase is taken as the medium of blood sugar measuring. And the range of measuring glucose is about 50mg/dL - 500mgl/dL. It has better linear for the results and fit coefficient arrives at 0.985. Its sensitivity of measurement is higher than current glucose biosensor obviously. A single chip microcomputer, AD mu C812, is used for central control processor of the instrument parts. It measures the output of microampere level currency, which is conduced by blood sugar reacting with the glucose oxidase on the enzyme electrode. And at the same time, the microampere level currency is amplified, processed. Then the results are displayed on LCD. The apparatus are better for measuring blood sugar, and the results are consistent with what the large biochemical instruments get.

Competing charge transfer pathways at the photosystem II-electrode interface

PubMed Central

Zhang, Jenny Z.; Sokol, Katarzyna P.; Paul, Nicholas; Romero, Elisabet; van Grondelle, Rienk; Reisner, Erwin

2016-01-01

The integration of the water-oxidation enzyme, photosystem II (PSII), into electrodes allows the electrons extracted from water-oxidation to be harnessed for enzyme characterization and driving novel endergonic reactions. However, PSII continues to underperform in integrated photoelectrochemical systems despite extensive optimization efforts. Here, we performed protein-film photoelectrochemistry on spinach and Thermosynechococcus elongatus PSII, and identified a competing charge transfer pathway at the enzyme-electrode interface that short-circuits the known water-oxidation pathway: photo-induced O2 reduction occurring at the chlorophyll pigments. This undesirable pathway is promoted by the embedment of PSII in an electron-conducting matrix, a common strategy of enzyme immobilization. Anaerobicity helps to recover the PSII photoresponses, and unmasked the onset potentials relating to the QA/QB charge transfer process. These findings have imparted a fuller understanding of the charge transfer pathways within PSII and at photosystem-electrode interfaces, which will lead to more rational design of pigment-containing photoelectrodes in general. PMID:27723748

Immobilisation of enzymes on poly(aniline)-poly(anion) composite films. Preparation of bioanodes for biofuel cell applications.

PubMed

Simon, Evelyne; Halliwell, Catherine M; Toh, Chee Seng; Cass, Anthony E G; Bartlett, Philip N

2002-01-01

Immobilisation of enzymes is important for applications such as biosensors or biofuel cells. A poly(histidine) tag had been introduced on the C terminus of a lactate dehydrogenase enzyme. This mutant enzyme was then immobilised onto poly(aniline) (PANi)-poly(anion) composite films, PANi-poly(vinylsulfonate) (PVS) or PANi-poly(acrylate) (PAA). The NADH produced by the immobilised enzyme in the presence of beta-nicotinamide adenine dinucleotide (NAD(+)) and lactate is oxidised at the poly(aniline)-coated electrode at 0.05 to 0.1 V vs. saturated calomel electrode (SCE) at 35 degrees C.

Gold nanoparticles/4-aminothiophenol interfaces for direct electron transfer of horseradish peroxidase: Enzymatic orientation and modulation of sensitivity towards hydrogen peroxide detection.

PubMed

Huerta-Miranda, G A; Arrocha-Arcos, A A; Miranda-Hernández, M

2018-08-01

Hydrogen peroxide electrochemical detection by horseradish peroxidase has been widely studied. The use of gold nanoparticles to prepare electrode/enzyme bioconjugates has attracted attention due to their catalytic properties. In this work, it is reported the use of gold nanoparticles and 4-aminothiophenol as a scaffold to obtain a suitable matrix for enzyme bioconjugation with horseradish peroxidase. A critical factor in biosensors design and development is the enzymatic electrochemical activity understanding. Comparison of voltammetric studies of the heme prosthetic group showed a reversible electrochemical behavior when the enzymes were immobilized in a well-dispersed gold deposit; on the other hand, a discrete redox response was observed on a randomly deposited gold electrode. These results show that the distance between enzymes is essential. Hydrogen peroxide catalysis and the enzymatic behavior were analyzed considering two types of nanoparticles dispositions. The catalytic behavior observed in the well-dispersed nanoparticles configuration suggests a preserved enzyme folding, a decrease of steric impediments, and appears to be a better immobilization strategy. In contrast, the randomly electrodeposited gold electrode decreased the enzyme orientation and the electrochemical activity. The advantages of this methodology are the electrode fabrication affordable cost and the enzymatic direct electron transfer response improvement. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast and easy enzyme immobilization by photoinitiated polymerization for efficient bioelectrochemical devices.

PubMed

Suraniti, Emmanuel; Studer, Vincent; Sojic, Neso; Mano, Nicolas

2011-04-01

Immobilization and electrical wiring of enzymes is of particular importance for the elaboration of efficient biosensors and can be cumbersome. Here, we report a fast and easy protocol for enzyme immobilization, and as a proof of concept, we applied it to the immobilization of bilirubin oxidase, a labile enzyme. In the first step, bilirubin oxidase is mixed with a redox hydrogel "wiring" the enzyme reaction centers to electrodes. Then, this adduct is covered by an outer layer of PEGDA made by photoinitiated polymerization of poly(ethylene-glycol) diacrylate (PEGDA) and a photoclivable precursor, DAROCUR. This two-step protocol is 18 times faster than the current state-of-the-art protocol and leads to currents 25% higher. In addition, the outer layer of PEGDA acts as a protective layer increasing the lifetime of the electrode by 100% when operating continuously for 2000 s and by 60% when kept in dry state for 24 h. This new protocol is particularly appropriate for labile enzymes that quickly denaturate. In addition, by tuning the ratio PEGDA/DAROCUR, it is possible to make the enzyme electrodes even more active or more stable.

Enzyme-based logic gates and circuits-analytical applications and interfacing with electronics.

PubMed

Katz, Evgeny; Poghossian, Arshak; Schöning, Michael J

2017-01-01

The paper is an overview of enzyme-based logic gates and their short circuits, with specific examples of Boolean AND and OR gates, and concatenated logic gates composed of multi-step enzyme-biocatalyzed reactions. Noise formation in the biocatalytic reactions and its decrease by adding a "filter" system, converting convex to sigmoid response function, are discussed. Despite the fact that the enzyme-based logic gates are primarily considered as components of future biomolecular computing systems, their biosensing applications are promising for immediate practical use. Analytical use of the enzyme logic systems in biomedical and forensic applications is discussed and exemplified with the logic analysis of biomarkers of various injuries, e.g., liver injury, and with analysis of biomarkers characteristic of different ethnicity found in blood samples on a crime scene. Interfacing of enzyme logic systems with modified electrodes and semiconductor devices is discussed, giving particular attention to the interfaces functionalized with signal-responsive materials. Future perspectives in the design of the biomolecular logic systems and their applications are discussed in the conclusion. Graphical Abstract Various applications and signal-transduction methods are reviewed for enzyme-based logic systems.

Bienzyme bionanomultilayer electrode for glucose biosensing based on functional carbon nanotubes and sugar-lectin biospecific interaction.

PubMed

Chen, Huan; Xi, Fengna; Gao, Xia; Chen, Zhichun; Lin, Xianfu

2010-08-01

Bienzyme bionanomultilayer electrode for glucose biosensing was constructed based on functional carbon nanotubes and sugar-lectin biospecific interaction through layer-by-layer (LBL) assembly. After being functionalized by wrapping with polyelectrolyte, multiwalled carbon nanotubes (MCNTs) were water soluble and positively charged. MCNT-bienzyme bionanomultilayer electrode was then fabricated by LBL assembly of horseradish peroxidase (HRP) and glucose oxidase (GOD) on functional MCNT modified electrode. The attachment of the MCNT-bienzyme bionanomultilayer with the underlying electrode and each layer in the bionanomultilayer was based on reliably electrostatic or sugar-lectin biospecific interaction. The developed bienzyme biosensor exhibited fast amperometric response for the determination of glucose. The linear response of the developed biosensor for the determination of glucose ranged from 2.0 x 10(-6) to 1.7 x 10(-4) M with a detection limit of 2.5 x 10(-7) M. The biosensor can be used directly to determine glucose in serum. The construction of the bienzyme biosensor showed potential for the preparation of MCNT-enzyme nanocomposite with controllability and high performance. Copyright 2010 Elsevier Inc. All rights reserved.

Bioelectrochemistry of heme peptide at seamless three-dimensional carbon nanotubes/graphene hybrid films for highly sensitive electrochemical biosensing.

PubMed

Komori, Kikuo; Terse-Thakoor, Trupti; Mulchandani, Ashok

2015-02-18

A seamless three-dimensional hybrid film consisting of carbon nanotubes grown at the graphene surface (CNTs/G) is a promising material for the application to highly sensitive enzyme-based electrochemical biosensors. The CNTs/G film was used as a conductive nanoscaffold for enzymes. The heme peptide (HP) was immobilized on the surface of the CNTs/G film for amperometric sensing of H2O2. Compared with flat graphene electrodes modified with HP, the catalytic current for H2O2 reduction at the HP-modified CNTs/G electrode increased due to the increase in the surface coverage of HP. In addition, microvoids in the CNTs/G film contributed to diffusion of H2O2 to modified HP, resulting in the enhancement of the catalytic cathodic currents. The kinetics of the direct electron transfer from the CNTs/G electrode to compound I and II of modified HP was also analyzed.

Development of Silicalite/Glucose Oxidase-Based Biosensor and Its Application for Glucose Determination in Juices and Nectars

NASA Astrophysics Data System (ADS)

Dudchenko, Oleksandr Ye; Pyeshkova, Viktoriya M.; Soldatkin, Oleksandr O.; Akata, Burcu; Kasap, Berna O.; Soldatkin, Alexey P.; Dzyadevych, Sergei V.

2016-02-01

The application of silicalite for improvement of enzyme adsorption on new stainless steel electrodes is reported. Glucose oxidase (GOx) was immobilized by two methods: cross-linking by glutaraldehyde (GOx-GA) and cross-linking by glutaraldehyde along with GOx adsorption on silicalite-modified electrode (SME) (GOx-SME-GA). The GOx-SME-GA biosensors were characterized by a four- to fivefold higher sensitivity than GOx-GA biosensor. It was concluded that silicalite together with GA sufficiently enhances enzyme adhesion on stainless steel electrodes. The developed GOx-SME-GA biosensors were characterized by good reproducibility of biosensor preparation (relative standard deviation (RSD)—18 %), improved signal reproducibility (RSD of glucose determination was 7 %), and good storage stability (29 % loss of activity after 18-day storage). A series of fruit juices and nectars was analyzed using GOx-SME-GA biosensor for determination of glucose concentration. The obtained results showed good correlation with the data of high-performance liquid chromatography (HPLC) ( R = 0.99).

Direct electrochemistry of dopamine on gold-Agaricus bisporus laccase enzyme electrode: characterization and quantitative detection.

PubMed

Shervedani, Reza Karimi; Amini, Akbar

2012-04-01

Direct electrochemistry of a new laccase enzyme immobilized on gold and its application as a biosensor for dopamine (DA) are investigated by voltammetry and electrochemical impedance spectroscopy. The sensor demonstrated a redox adsorption behavior with E(0') = + 180 mV vs. Ag/AgCl for immobilized Agaricus bisporus laccase (LacAB) enzyme. The MPA platform was assembled on Au with and without utilization of ultrasounds. Excellent results were obtained by using the enzyme electrode fabricated based on MPA assembled with sonication. The LacAB immobilized in this condition showed a large electrocatalytic activity for oxidation of DA. Accordingly, a third-generation (mediator free) biosensor was constructed for DA. The DA concentration could be measured in the linear range of 0.5 to 13.0 and 47.0 to 430.0 μmol L(-1) with correlation coefficients of 0.999 and 0.989, respectively, and a detection limit of 29.0 nmol L(-1). The biosensor was successfully tested for determination of DA in human blood plasma and pharmaceutical samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Polyluminol/hydrogel composites as new electrochemiluminescent-active sensing layers.

PubMed

Leca-Bouvier, Béatrice D; Sassolas, Audrey; Blum, Loïc J

2014-09-01

This paper reports on electrochemiluminescent sensors and biosensors based on polyluminol/hydrogel composite sensing layers using chemical or biological membranes as hydrogel matrices. In this work, luminol is electropolymerized under near-neutral conditions onto screen-printed electrode (SPE)-supported hydrogel films. The working electrode coated with a hydrogel film is soaked in a solution containing monomeric luminol units, allowing the monomeric luminol units to diffuse inside the porous matrix to the electrode surface where they are electropolymerized by cyclic voltammetry (CV). Sensors and enzymatic biosensors for H2O2 and choline detection, respectively, have been developed, using choline oxidase (ChOD) as a model enzyme. In this case, hydrogel is used both as the enzymatic immobilization matrix and as a template for the electrosynthesis of polyluminol. The enzyme was immobilized by entrapment in the gel matrix during its formation before electropolymerization of the monomer. Several parameters have been optimized in terms of polymerization conditions, enzyme loading, and average pore size. Using calcium alginate or tetramethoxysilane (TMOS)-based silica as porous matrix, H2O2 and choline detection are reported down to micromolar concentrations with three orders of magnitude wide dynamic ranges starting from 4 × 10(-7) M. Polyluminol/hydrogel composites appear as suitable electrochemiluminescence (ECL)-active sensing layers for the design of new reagentless and disposable easy-to-use optical sensors and biosensors, using conventional TMOS-based silica gel or the more original and easier to handle calcium alginate, reported here for the first time in such a configuration, as the biocompatible hydrogel matrix.

Laccase-based biocathodes: Comparison of chitosan and Nafion.

PubMed

El Ichi-Ribault, S; Zebda, A; Laaroussi, A; Reverdy-Bruas, N; Chaussy, D; Belgacem, M N; Suherman, A L; Cinquin, P; Martin, D K

2016-09-21

Chitosan and Nafion(®) are both reported as interesting polymers to be integrated into the structure of 3D electrodes for biofuel cells. Their advantage is mainly related to their chemical properties, which have a positive impact on the stability of electrodes such as the laccase-based biocathode. For optimal function in implantable applications the biocathode requires coating with a biocompatible semi-permeable membrane that is designed to prevent the loss of enzyme activity and to protect the structure of the biocathode. Since such membranes are integrated into the electrodes ultimately implanted, they must be fully characterized to demonstrate that there is no interference with the performance of the electrode. In the present study, we demonstrate that chitosan provides superior stability compared with Nafion(®) and should be considered as an optimum solution to enhance the biocompatibility and the stability of 3D bioelectrodes. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrically contacted enzyme based on dual hairpin DNA structure and its application for amplified detection of Hg2+.

PubMed

Wang, Guangfeng; Huang, Hao; Zhang, Xiaojun; Wang, Lun

2012-05-15

In the present study, based on a dual hairpin DNA structure, a novel system of electrically contacted enzyme and its signal amplification for ultrasensitive detection of Hg(2+) was demonstrated. In the presence of Hg(2+), with the interaction of thymine-Hg(2+)-thymine (T-Hg(2+)-T), DNA sequence dully labeled with ferrocene (Fc) at 5' end and horseradish peroxidase (HRP) at 3' end, hybridized to the capture probe and formed the dual hairpin structure on the electrode. Fc unit acts as a relay that electrically contacts HRP with the electrode and activates the bioelectrocatalyzed reduction of H(2)O(2). And based on the bioelectrocatalyzed signal amplification of the presented system, Hg(2+) could be quantitatively detected in the range of 10(-10)-10(-6)M with a low detection limit of 52 pM. And it also demonstrated excellent selectivity against other interferential metal ions. Copyright © 2012 Elsevier B.V. All rights reserved.

Ion and Bio-Selective Membrane Electrodes.

ERIC Educational Resources Information Center

Rechnitz, Garry A.

1983-01-01

Discusses topics on membrane electrodes corresponding to approximately six hours of lecture time. These include glass, liquid, crystal, gas-sensing membrane electrodes as well as enzyme and other bioselective membrane electrodes. Instructional strategies and other topics which might be discussed are provided. (JN)

Solution Process Synthesis of High Aspect Ratio ZnO Nanorods on Electrode Surface for Sensitive Electrochemical Detection of Uric Acid

NASA Astrophysics Data System (ADS)

Ahmad, Rafiq; Tripathy, Nirmalya; Ahn, Min-Sang; Hahn, Yoon-Bong

2017-04-01

This study demonstrates a highly stable, selective and sensitive uric acid (UA) biosensor based on high aspect ratio zinc oxide nanorods (ZNRs) vertical grown on electrode surface via a simple one-step low temperature solution route. Uricase enzyme was immobilized on the ZNRs followed by Nafion covering to fabricate UA sensing electrodes (Nafion/Uricase-ZNRs/Ag). The fabricated electrodes showed enhanced performance with attractive analytical response, such as a high sensitivity of 239.67 μA cm-2 mM-1 in wide-linear range (0.01-4.56 mM), rapid response time (~3 s), low detection limit (5 nM), and low value of apparent Michaelis-Menten constant (Kmapp, 0.025 mM). In addition, selectivity, reproducibility and long-term storage stability of biosensor was also demonstrated. These results can be attributed to the high aspect ratio of vertically grown ZNRs which provides high surface area leading to enhanced enzyme immobilization, high electrocatalytic activity, and direct electron transfer during electrochemical detection of UA. We expect that this biosensor platform will be advantageous to fabricate ultrasensitive, robust, low-cost sensing device for numerous analyte detection.

Ultrasensitive aptamer-based protein detection via a dual amplified biocatalytic strategy

PubMed Central

Xiang, Yun; Zhang, Yuyong; Qian, Xiaoqing; Chai, Yaqin; Wang, Joseph; Yuan, Ruo

2010-01-01

We present an ultrasensitive aptasensor for electronic monitoring of proteins through a dual amplified strategy in this paper. The target protein thrombin is sandwiched between an electrode surface confined aptamer and an aptamer-enzyme-carbon nanotube bioconjugate. The analytical signal amplification is achieved by coupling the signal amplification nature of multiple enzymes with the biocatalytic signal enhancement of redox-recycling. Our novel dramatic signal amplification strategy, with a detection limit of 8.3 fM, shows about 4 orders of magnitude improvement in sensitivity for thrombin detection compared to other universal single enzyme-based assay. This makes our approach an attractive alternative to other common PCR-based signal amplification in ultralow level of protein detection. PMID:20452761

Glucose oxidase/cellulose-carbon nanotube composite paper as a biocompatible bioelectrode for biofuel cells.

PubMed

Won, Keehoon; Kim, Young-Hoo; An, Seulji; Lee, Hye Jung; Park, Saerom; Choi, Yong-Keun; Kim, Ji Hyeon; Hwang, Hak-In; Kim, Hyung Joo; Kim, Hyungsup; Lee, Sang Hyun

2013-11-01

Biofuel cells are devices for generating electrical energy directly from chemical energy of renewable biomass using biocatalysts such as enzymes. Efficient electrical communication between redox enzymes and electrodes is essential for enzymatic biofuel cells. Carbon nanotubes (CNTs) have been recognized as ideal electrode materials because of their high electrical conductivity, large surface area, and inertness. Electrodes consisting entirely of CNTs, which are known as CNT paper, have high surface areas but are typically weak in mechanical strength. In this study, cellulose (CL)-CNT composite paper was fabricated as electrodes for enzymatic biofuel cells. This composite electrode was prepared by vacuum filtration of CNTs followed by reconstitution of cellulose dissolved in ionic liquid, 1-ethyl-3-methylimidazolium acetate. Glucose oxidase (GOx), which is a redox enzyme capable of oxidizing glucose as a renewable fuel using oxygen, was immobilized on the CL-CNT composite paper. Cyclic voltammograms revealed that the GOx/CL-CNT paper electrode showed a pair of well-defined peaks, which agreed well with that of FAD/FADH2, the redox center of GOx. This result clearly shows that the direct electron transfer (DET) between the GOx and the composite electrode was achieved. However, this DET was dependent on the type of CNTs. It was also found that the GOx immobilized on the composite electrode retained catalytic activity for the oxidation of glucose.

Role of carbon nanotubes in electroanalytical chemistry: a review.

PubMed

Agüí, Lourdes; Yáñez-Sedeño, Paloma; Pingarrón, José M

2008-08-01

This review covers recent advances in the development of new designs of electrochemical sensors and biosensors that make use of electrode surfaces modification with carbon nanotubes. Applications based on carbon nanotubes-driven electrocatalytic effects, and the construction and analytical usefulness of new hybrid materials with polymers or other nanomaterials will be treated. Moreover, electrochemical detection using carbon nanotubes-modified electrodes as detecting systems in separation techniques such as high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) will be also considered. Finally, the preparation of electrochemical biosensors, including enzyme electrodes, immunosensors and DNA biosensors, in which carbon nanotubes play a significant role in their sensing performance will be separately considered.

Enzyme-modified nanoporous gold-based electrochemical biosensors.

PubMed

Qiu, Huajun; Xue, Luyan; Ji, Guanglei; Zhou, Guiping; Huang, Xirong; Qu, Yinbo; Gao, Peiji

2009-06-15

On the basis of the unique physical and chemical properties of nanoporous gold (NPG), which was obtained simply by dealloying Ag from Au/Ag alloy, an attempt was made in the present study to develop NPG-based electrochemical biosensors. The NPG-modified glassy carbon electrode (NPG/GCE) exhibited high-electrocatalytic activity toward the oxidation of nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H(2)O(2)), which resulted in a remarkable decrease in the overpotential of NADH and H(2)O(2) electro-oxidation when compared with the gold sheet electrode. The high density of edge-plane-like defective sites and large specific surface area of NPG should be responsible for the electrocatalytic behavior. Such electrocatalytic behavior of the NPG/GCE permitted effective low-potential amperometric biosensing of ethanol or glucose via the incorporation of alcohol dehydrogenase (ADH) or glucose oxidase (GOD) within the three-dimensional matrix of NPG. The ADH- and GOD-modified NPG-based biosensors showed good analytical performance for biosensing ethanol and glucose due to the clean, reproducible and uniformly distributed microstructure of NPG. The stabilization effect of NPG on the incorporated enzymes also made the constructed biosensors very stable. After 1 month storage at 4 degrees C, the ADH- and GOD-based biosensors lost only 5.0% and 4.2% of the original current response. All these indicated that NPG was a promising electrode material for biosensors construction.

Alcohol vapour detection at the three phase interface using enzyme-conducting polymer composites.

PubMed

Winther-Jensen, Orawan; Kerr, Robert; Winther-Jensen, Bjorn

2014-02-15

Immobilisation of enzymes on a breathable electrode can be useful for various applications where the three-phase interface between gas or chemical vapour, electrolyte and electrode is crucial for the reaction. In this paper, we report the further development of the breathable electrode concept by immobilisation of alcohol dehydrogenase into vapour-phase polymerised poly(3,4-ethylene dioxythiophene) that has been coated onto a breathable membrane. Typical alcohol sensing, whereby the coenzyme β-Nicotinamide adenine dinucleotide (NADH) is employed as a redox-mediator, was successfully used as a model reaction for the oxidation of ethanol. This indicates that the ethanol vapour from the backside of the membrane has access to the active enzyme embedded in the electrode. The detecting range of the sensor is suitable for the detection of ethanol in fruit juices and for the baseline breath ethanol concentration of drunken driving. After continuous operation for 4.5h the system only showed a 20% decrease in the current output. The electrodes maintained 62% in current output after being refrigerated for 76 days. This work is continuing the progress of the immobilisation of specific enzymes for certain electrochemical reactions whereby the three-phase interface has to be maintained and/or the simultaneous separation of gas from liquid is required. © 2013 Elsevier B.V. All rights reserved.

Towards a novel bioelectrocatalytic platform based on “wiring” of pyrroloquinoline quinone-dependent glucose dehydrogenase with an electrospun conductive polymeric fiber architecture

NASA Astrophysics Data System (ADS)

Gladisch, Johannes; Sarauli, David; Schäfer, Daniel; Dietzel, Birgit; Schulz, Burkhard; Lisdat, Fred

2016-01-01

Electrospinning is known as a fabrication technique for electrode architectures that serve as immobilization matrices for biomolecules. The current work demonstrates a novel approach to construct a conductive polymeric platform, capable not only of immobilization, but also of electrical connection of the biomolecule with the electrode. It is produced upon electrospinning from mixtures of three different highly conductive sulfonated polyanilines and polyacrylonitrile on ITO electrodes. The resulting fiber mats are with a well-retained conductivity. After coupling the enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) to polymeric structures and addition of the substrate glucose an efficient bioelectrocatalysis is demonstrated. Depending on the choice of the sulfonated polyanilline mediatorless bioelectrocatalysis starts at low potentials; no large overpotential is needed to drive the reaction. Thus, the electrospun conductive immobilization matrix acts here as a transducing element, representing a promising strategy to use 3D polymeric scaffolds as wiring agents for active enzymes. In addition, the mild and well reproducible fabrication process and the active role of the polymer film in withdrawing electrons from the reduced PQQ-GDH lead to a system with high stability. This could provide access to a larger group of enzymes for bioelectrochemical applications including biosensors and biofuel cells.

Preparation of biosensors by immobilization of polyphenol oxidase in conducting copolymers and their use in determination of phenolic compounds in red wine.

PubMed

Böyükbayram, A Elif; Kiralp, Senem; Toppare, Levent; Yağci, Yusuf

2006-10-01

Electrochemically produced graft copolymers of thiophene capped polytetrahydofuran (TPTHF1 and TPTHF2) and pyrrole were achieved by constant potential electrolysis using sodium dodecylsulfate (SDS) as the supporting electrolyte. Characterizations were based on Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Electrical conductivities were measured by the four-probe technique. Novel biosensors for phenolic compounds were constructed by immobilizing polyphenol oxidase (PPO) into conducting copolymers prepared by electropolymerization of pyrrole with thiophene capped polytetrahydrofuran. Kinetic parameters, maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) and optimum conditions regarding temperature and pH were determined for the immobilized enzyme. Operational stability and shelf-life of the enzyme electrodes were investigated. Enzyme electrodes of polyphenol oxidase were used to determine the amount of phenolic compounds in two brands of Turkish red wines and found very useful owing to their high kinetic parameters and wide pH working range.

On-line removal of redox-active interferents by a porous electrode before amperometric blood glucose determination.

PubMed

Deng, Chunyan; Peng, Yong; Su, Lei; Liu, You-Nian; Zhou, Feimeng

2012-03-16

A porous reticulated vitreous carbon (RVC) electrode and a disk electrode coupled in tandem in an electrochemical flow cell has been used for electrolytic removal of interferents before amperometric glucose detection. The electrolytic efficiency at the upstream RVC electrode is 100% at a flow rate of 0.1 mL min(-1) or lower. Potential interferents such as acetaminophen, ascorbic acid, and uric acid can be completely eliminated by electrolysis at the RVC electrode. A mixed monolayer comprising glucose oxidase (GOD) and ferrocenyl-1-undecanethiol preformed at the downstream gold disk electrode was used as a mediator-based amperometric glucose sensor. The dependence of the amperometric current on the glucose concentration exhibits good linearity across over three orders of magnitude. The glucose measurements were also found to be reproducible (RSD<3.5%) and accurate. Unlike the chemiluminescence method, this device obviates the use of carcinogenic substrates and the glucose sensor performance is independent of the oxygen present in sample. On the basis that the RVC electrode requires minimal cleanup and the GOD-modified electrode remains stable for a week, the electrochemical flow cell should be amenable for automated on-line removal of redox interferents for other types of enzyme-based biosensors. Copyright © 2012 Elsevier B.V. All rights reserved.

Prototype amperometric biosensor for sialic acid determination.

PubMed

Marzouk, Sayed A M; Ashraf, S S; Tayyari, Khawla A Al

2007-02-15

This paper describes the first report on the development, characterization, and applications of a prototype amperometric biosensor for free sialic acid (SA). The sensor was constructed by the coimmobilization of two enzymes, i.e., N-acetylneuraminic acid aldolase and pyruvate oxidase, on a polyester microporous membrane, which was then mounted on top of a platinum disk electrode. The SA biosensor operation was based on the sequential action of the two enzymes to ultimately produce hydrogen peroxide, which was then detected by anodic amperometry at the platinum electrode. The surface of the platinum electrode was coated with an electropolymeric layer to enhance the biosensor selectivity in the presence of interfering oxidizable species. Optimization of the enzyme layer composition resulted in a fast and steady current response in phosphate buffer pH 7.2 at 37 degrees C. The limit of detection was 10 microM, and the response was linear to 3.5 mM (r = 0.9987). The prepared SA biosensors retained approximately 85% of their initial sensitivity after 8 days and showed excellent response reproducibility (CV = 2.3%). Utilization of a third enzyme, sialidase, expanded the scope of the present SA biosensor to determine bound sialic acid as well. The merits of the described biosensor allowed its successful application in determining SA in biological and pharmaceutical samples. The obtained results indicated that the presented SA biosensor should be a useful bioanalytical tool in several biological and clinical applications such as screening of SA as a nonspecific tumor marker as well as monitoring of tumor therapy.

Membrane Bioprobe Electrodes

ERIC Educational Resources Information Center

Rechnitz, Garry A.

1975-01-01

Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

A review study of (bio)sensor systems based on conducting polymers.

PubMed

Ates, Murat

2013-05-01

This review article concentrates on the electrochemical biosensor systems with conducting polymers. The area of electro-active polymers confined to different electrode surfaces has attracted great attention. Polymer modified carbon substrate electrodes can be designed through polymer screening to provide tremendous improvements in sensitivity, selectivity, stability and reproducibility of the electrode response to detect a variety of analytes. The electro-active films have been used to entrap different enzymes and/or proteins at the electrode surface, but without obvious loss of their bioactivity for the development of biosensors. Electropolymerization is a well-known technique used to immobilize biomaterials to the modified electrode surface. Polymers might be covalently bonding to enzymes or proteins; therefore, thickness, permeation and charge transport characteristics of the polymeric films can be easily and precisely controlled by modulating the electrochemical parameters for various electrochemical techniques, such as chronoamperometry, chronopotentiometry, cyclic voltammetry, and differential pulse voltammetry. This review article is divided into three main parts as given in the table of contents related to the immobilization process of some important conducting polymers, polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene), polycarbazole, polyaniline, polyphenol, poly(o-phenylenediamine), polyacetylene, polyfuran and their derivatives. A total of 216 references are cited in this review article. The literature reviewed covers a 7 year period beginning from 2005. Copyright © 2013 Elsevier B.V. All rights reserved.

Bio-functionalization of conductive textile materials with redox enzymes

NASA Astrophysics Data System (ADS)

Kahoush, M.; Behary, N.; Cayla, A.; Nierstrasz, V.

2017-10-01

In recent years, immobilization of oxidoreductase enzymes on electrically conductive materials has played an important role in the development of sustainable bio-technologies. Immobilization process allows the re-use of these bio-catalysts in their final applications. In this study, different methods of immobilizing redox enzymes on conductive textile materials were used to produce bio-functionalized electrodes. These electrodes can be used for bio-processes and bio-sensing in eco-designed applications in domains such as medicine and pollution control. However, the main challenge facing the stability and durability of these electrodes is the maintenance of the enzymatic activity after the immobilization. Hence, preventing the enzyme’s denaturation and leaching is a critical factor for the success of the immobilization processes.

Evaluation of non-specific binding suppression schemes for neutravidin and alkaline phosphatase at the surface of reticulated vitreous carbon electrodes.

PubMed

Shedge, Hemangi Y; Creager, Stephen E

2010-01-11

Non-specific binding (NSB) of high-molecular-weight proteins onto electrode surfaces can complicate the application of electroanalytical techniques to clinical and environmental research, particularly in biosensor applications. We present herein various strategies to modify the surface of reticulated vitreous carbon (RVC) electrodes to suppress non-specific binding of biomolecules onto its surface. Non-specific binding and specific binding (SB) of two enzyme conjugates, neutravidin-alkaline phosphatase (NA-ALP) and biotinylated alkaline phosphatase (B-ALP), and also neutravidin itself, were studied using hydroquinone diphosphate (HQDP) as an enzyme substrate for ALP inside the pores of RVC electrodes that had been subjected to various modification schemes. The extent of NSB and SB of these biomolecules inside RVC pores was assessed by measuring the initial rate of generation of an electroactive product, hydroquinone (HQ), of the enzyme-catalyzed reaction, using linear scan voltammetry (LSV) for HQ detection. Electrodes functionalized with phenylacetic acid and poly(ethylene glycol) (PEG) showed low NSB and high SB (when biotin capture ligands were included in the modification scheme) in comparison with unmodified electrodes and RVC electrodes modified in other ways. A simple sandwich bioassay for neutravidin was performed on the RVC electrode with the lowest NSB. A concentration detection limit of 52+/-2 ng mL(-1) and an absolute detection limit of 5.2+/-0.2 ng were achieved for neutravidin when this assay was performed using a 100 microL sample size.

A glucose biosensor based on direct electrochemistry of glucose oxidase immobilized on nitrogen-doped carbon nanotubes.

PubMed

Deng, Shengyuan; Jian, Guoqiang; Lei, Jianping; Hu, Zheng; Ju, Huangxian

2009-10-15

A novel biosensor for glucose was prepared by immobilizing glucose oxidase (GOx) on nitrogen-doped carbon nanotubes (CNx-MWNTs) modified electrode. The CNx-MWNTs membrane showed an excellent electrocatalytic activity toward the reduction of O(2) due to its diatomic side-on adsorption on CNx-MWNTs. The nitrogen doping accelerated the electron transfer from electrode surface to the immobilized GOx, leading to the direct electrochemistry of GOx. The biofunctional surface showed good biocompatibility, excellent electron-conductive network and large surface-to-volume ratio, which were characterized by scanning electron microscopy, contact angle and electrochemical impedance technique. The direct electron transfer of immobilized GOx led to stable amperometric biosensing for glucose with a linear range from 0.02 to 1.02 mM and a detection limit of 0.01 mM (S/N=3). These results indicated that CNx-MWNTs are good candidate material for construction of the third-generation enzyme biosensors based on the direct electrochemistry of immobilized enzymes.

A reagentless amperometric biosensor for alcohol detection in column liquid chromatography based on co-immobilized peroxidase and alcohol oxidase in carbon paste.

PubMed

Johansson, K; Jönsson-Pettersson, G; Gorton, L; Marko-Varga, G; Csöregi, E

1993-12-01

A reagentless carbon paste electrode chemically modified with covalently bound alcohol oxidase and horse-radish peroxidase was examined as a selective sensor in flow injection and column liquid chromatography. A combination of carbodiimide, glutaraldehyde, and polyethyleneimine was used for immobilizing the enzymes in the paste. The surface of the electrodes was protected by first forming a layer of electropolymerized ortho-phenylenediamine followed by deposition of a cation exchange membrane (Eastman AQ 29D). The electrodes were used for detection of hydrogen peroxide, methanol, ethanol, propanol, isopropanol, and butanol. Preliminary investigations of the use of this sensor for bioprocess control are reported.

Mechanism of amperometric biosensor with electronic-type-controlled carbon nanotube

NASA Astrophysics Data System (ADS)

Hidaka, Hiroki; Nowaki, Kohei; Muguruma, Hitoshi

2016-03-01

An amperometric enzyme biosensor with electronic-type-controlled (metallic and semiconducting) single-walled carbon nanotubes (CNTs) is presented. In this research, we investigate how the electronic types of CNTs influence the amperometric response of enzyme biosensors and what their working mechanisms are. The biosensor of interest is for glucose detection using enzyme glucose oxidase (GOD). In the presence of oxygen, the response of a metallic CNT-GOD electrode was 2.5 times more sensitive than that of a semiconducting CNT-GOD electrode. In contrast, in the absence of oxygen, the response of the semiconducting CNT-GOD electrode was retained, whereas that of the metallic CNT-GOD electrode was significantly reduced. This indicates that direct electron transfer occurred with the semiconducting CNT-GOD electrode, whereas the metallic CNT-GOD electrode was dominated by a hydrogen peroxide pathway caused by an enzymatic reaction. Electrochemical impedance spectroscopy was used to show that the semiconducting CNT network has less resistance for electron transfer than the metallic CNT network. The optimized glucose biosensor revealed a sensitivity of 5.6 µA mM-1 cm-2 at +0.6 V vs Ag/AgCl, a linear dynamic range of 0.025-1.4 mM, and a response time of 8 s.

Nonenzymetic glucose sensing using carbon functionalized carbon doped ZnO nanorod arrays

NASA Astrophysics Data System (ADS)

Chakraborty, Pinak; Majumder, Tanmoy; Dhar, Saurab; Mondal, Suvra Prakash

2018-04-01

Fabrication of highly sensitive, long stability and low cost glucose sensors are attractive for biomedical applications and food industries. Most of the commercial glucose sensors are based on enzymatic detection which suffers from problems underlying in enzyme activities. Development of high sensitive, enzyme free sensors is a great challenge for next generation glucose sensing applications. In our study Zinc oxide nanorod sensing electrodes have been grown using low cost hydrothermal route and their nonenzymatic glucose sensing properties have been demonstrated with carbon functionalized, carbon doped ZnO nanorods (C-ZnO NRs) in neutral medium (0.1M PBS, pH 7.4) using cyclic voltammetry and amperometry measurements. The C-ZnO NRs electrodes demonstrated glucose sensitivity˜ 13.66 µAmM-1cm-2 in the concentration range 0.7 - 14 mM.

A membrane-based immunosensor for the analysis of the herbicide isoproturon.

PubMed

Baskeyfield, Damian E H; Davis, Frank; Magan, Naresh; Tothill, Ibtisam E

2011-08-12

A membrane based heterogeneous competitive enzyme-linked immunosorbent assay (ELISA) was used in this work to develop an immunosensor for the detection of a common herbicide, isoproturon. A screen-printed carbon working electrode with carbon counter and silver-silver chloride pseudo-reference electrode was utilized incorporating a membrane fixed into intimate contact with the working electrode to facilitate signal transduction. The membrane containing an immobilized isoproturon-ovalbumin conjugate was laminated onto the carbon working electrode and horseradish peroxidase (HRP) labeled polyclonal antibody was then applied for the competitive assay. Two different amperometric systems, hydroquinone and o-phenylenediamine (OPD) mediation reduction were utilised and the properties of the resultant sensors were compared. A flow injection apparatus was also developed utilising the immunosensor. Limits of detection for isoproturon (LLD(90)) were found to be as low as 0.84 ng mL(-1). The senor was also validated using spiked extracted soil samples and also isoproturon contaminated samples. Copyright © 2011 Elsevier B.V. All rights reserved.

The development of sensors and techniques for in situ water quality monitoring

NASA Technical Reports Server (NTRS)

Liu, C. C.

1976-01-01

Enzyme electrodes and chloride ion electrodes were investigated for in situ monitoring of water quality. Preliminary results show that miniature chloride ion electrodes and a phenol sensor are most promising in determining trace contaminants in water.

Design of nanostructured-based glucose biosensors

NASA Astrophysics Data System (ADS)

Komirisetty, Archana; Williams, Frances; Pradhan, Aswini; Konda, Rajini B.; Dondapati, Hareesh; Samantaray, Diptirani

2012-04-01

This paper presents the design of glucose sensors that will be integrated with advanced nano-materials, bio-coatings and electronics to create novel devices that are highly sensitive, inexpensive, accurate, and reliable. In the work presented, a glucose biosensor and its fabrication process flow have been designed. The device is based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nano-rods. Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability which are very crucial parameters to achieve high sensitivity. Amperometric enzyme electrodes based on glucose oxidase (GOx) are used due to their stability and high selectivity to glucose. The device also consists of silicon dioxide and titanium layers as well as platinum working and counter electrodes and a silver/silver chloride reference electrode. Currently, the biosensors are being fabricated using the process flow developed. Once completed, the sensors will be bio-functionalized and tested to characterize their performance, including their sensitivity and stability.

Redox hydrogel based bienzyme electrode for L-glutamate monitoring.

PubMed

Belay, A; Collins, A; Ruzgas, T; Kissinger, P T; Gorton, L; Csöregi, E

1999-02-01

Amperometric bienzyme electrodes based on coupled L-glutamate oxidase (GlOx) and horseradish peroxidase (HRP) were constructed for the direct monitoring of L-glutamate in a flow injection (FI)-system. The bienzyme electrodes were constructed by coating solid graphite rods with a premixed solution containing GlOx and HRP crosslinked with a redox polymer formed of poly(1-vinylimidazole) complexed with (osmium (4-4'-dimethylbpy)2 Cl)II/III. Poly(ethylene glycol) diglycidyl ether (PEGDGE) was used as the crosslinker and the modified electrodes were inserted as the working electrode in a conventional three electrode flow through amperometric cell operated at -0.05 V versus Ag¿AgCl (0.1 M KCl). The bienzyme electrode was optimized with regard to wire composition, Os-loading of the wires, enzyme ratios, coating procedure, flow rate, effect of poly(ethyleneimine) addition, etc. The optimized electrodes were characterized by a sensitivity of 88.36 +/- 0.14 microA mM(-1) cm(-2), a detection limit of 0.3 microM (calculated as three times the signal-to-noise ratio), a response time of less than 10 s and responded linearly between 0.3 and 250 microM (linear regression coefficient = 0.999) with an operational stability of only 3% sensitivity loss during 8 h of continuous FI operation at a sample throughput of 30 injections h(-1).

Strategies for "wiring" redox-active proteins to electrodes and applications in biosensors, biofuel cells, and nanotechnology.

PubMed

Nöll, Tanja; Nöll, Gilbert

2011-07-01

In this tutorial review the basic approaches to establish electrochemical communication between redox-active proteins and electrodes are elucidated and examples for applications in electrochemical biosensors, biofuel cells and nanotechnology are presented. The early stage of protein electrochemistry is described giving a short overview over electron transfer (ET) between electrodes and proteins, followed by a brief introduction into experimental procedures for studying proteins at electrodes and possible applications arising thereof. The article starts with discussing the electrochemistry of cytochrome c, the first redox-active protein, for which direct reversible ET was obtained, under diffusion controlled conditions and after adsorption to electrodes. Next, examples for the electrochemical study of redox enzymes adsorbed on electrodes and modes of immobilization are discussed. Shortly the experimental approach for investigating redox-active proteins adsorbed on electrodes is outlined. Possible applications of redox enzymes in electrochemical biosensors and biofuel cells working by direct ET (DET) and mediated ET (MET) are presented. Furthermore, the reconstitution of redox active proteins at electrodes using molecular wire-like units in order to "wire" the proteins to the electrode surface and possible applications in nanotechnology are discussed.

Microbial Biofilm Voltammetry: Direct Electrochemical Characterization of Catalytic Electrode-Attached Biofilms▿ †

PubMed Central

Marsili, Enrico; Rollefson, Janet B.; Baron, Daniel B.; Hozalski, Raymond M.; Bond, Daniel R.

2008-01-01

While electrochemical characterization of enzymes immobilized on electrodes has become common, there is still a need for reliable quantitative methods for study of electron transfer between living cells and conductive surfaces. This work describes growth of thin (<20 μm) Geobacter sulfurreducens biofilms on polished glassy carbon electrodes, using stirred three-electrode anaerobic bioreactors controlled by potentiostats and nondestructive voltammetry techniques for characterization of viable biofilms. Routine in vivo analysis of electron transfer between bacterial cells and electrodes was performed, providing insight into the main redox-active species participating in electron transfer to electrodes. At low scan rates, cyclic voltammetry revealed catalytic electron transfer between cells and the electrode, similar to what has been observed for pure enzymes attached to electrodes under continuous turnover conditions. Differential pulse voltammetry and electrochemical impedance spectroscopy also revealed features that were consistent with electron transfer being mediated by an adsorbed catalyst. Multiple redox-active species were detected, revealing complexity at the outer surfaces of this bacterium. These techniques provide the basis for cataloging quantifiable, defined electron transfer phenotypes as a function of potential, electrode material, growth phase, and culture conditions and provide a framework for comparisons with other species or communities. PMID:18849456

Highly sensitive and stable electrochemical sulfite biosensor incorporating a bacterial sulfite dehydrogenase.

PubMed

Kalimuthu, Palraj; Tkac, Jan; Kappler, Ulrike; Davis, Jason J; Bernhardt, Paul V

2010-09-01

This paper describes a highly sensitive electrochemical (voltammetric) determination of sulfite using a combination of Starkeya novella sulfite dehydrogenase (SDH), horse heart cytochrome c (cyt c), and a self-assembled monolayer of 11-mercaptoundecanol (MU) cast on a gold electrode. The biosensor was optimized in terms of pH and the ratio of cyt c/SDH. The electrocatalytic oxidation current of sulfite increased linearly from 1 to 6 microM at the enzyme-modified electrode with a correlation coefficient of 0.9995 and an apparent Michaelis constant (K(M,app)) of 43 microM. Using an amperometric method, the low detection limit for sulfite at the enzyme-modified electrode was 44 pM (signal-to-noise ratio = 3). The modified electrode retained a stable response for 3 days while losing only ca. 4% of its initial sensitivity during a 2 week storage period in 50 mM Tris buffer solution at 4 degrees C. The enzyme electrode was successfully used for the determination of sulfite in beer and white wine samples. The results of these electrochemical analyses agreed well with an independent spectrophotometric method using Ellman's reagent, but the detection limit was far superior using the electrochemical method.

Electron flow in multicenter enzymes: theory, applications, and consequences on the natural design of redox chains.

PubMed

Léger, Christophe; Lederer, Florence; Guigliarelli, Bruno; Bertrand, Patrick

2006-01-11

In protein film voltammetry, a redox enzyme is directly connected to an electrode; in the presence of substrate and when the driving force provided by the electrode is appropriate, a current flow reveals the steady-state turnover. We show that, in the case of a multicenter enzyme, this signal reports on the energetics and kinetics of electron transfer (ET) along the redox chain that wires the active site to the electrode, and this provides a new strategy for studying intramolecular ET. We propose a model which takes into account all the enzyme's redox microstates, and we prove it useful to interpret data for various enzymes. Several general ideas emerge from this analysis. Considering the reversibility of ET is a requirement: the usual picture, where ET is depicted as a series of irreversible steps, is oversimplified and lacks the important features that we emphasize. We give justification to the concept of apparent reduction potential on the time scale of turnover and we explain how the value of this potential relates to the thermodynamic and kinetic properties of the system. When intramolecular ET does not limit turnover, the redox chain merely mediates the driving force provided by the electrode or the soluble redox partner, whereas when intramolecular ET is slow, the enzyme behaves as if its active active site had apparent redox properties which depend on the reduction potentials of the relays. This suggests an alternative to the idea that redox chains are optimized in terms of speed: evolutionary pressure may have resulted in slowing down intramolecular ET in order to tune the enzyme's "operating potential".

A hydrogen fuel cell for rapid, enzyme-catalysed organic synthesis with continuous monitoring.

PubMed

Wan, Lei; Megarity, Clare F; Siritanaratkul, Bhavin; Armstrong, Fraser A

2018-01-23

A one-pot fuel cell for specific, enzyme-catalysed organic synthesis, with continuous monitoring of rate and reaction progress, combines an electrode catalysing rapid, reversible and diffusion-controlled interconversion of NADP + and NADPH with a Pt electrode catalysing 2H + /H 2 interconversion. This Communication demonstrates its performance and characteristics using the reductive amination of 2-oxoglutarate as a test system.

Integration of Enzymes in Polyaniline-Sensitized 3D Inverse Opal TiO2 Architectures for Light-Driven Biocatalysis and Light-to-Current Conversion.

PubMed

Riedel, Marc; Lisdat, Fred

2018-01-10

Inspired by natural photosynthesis, coupling of artificial light-sensitive entities with biocatalysts in a biohybrid format can result in advanced photobioelectronic systems. Herein, we report on the integration of sulfonated polyanilines (PMSA1) and PQQ-dependent glucose dehydrogenase (PQQ-GDH) into inverse opal TiO 2 (IO-TiO 2 ) electrodes. While PMSA1 introduces sensitivity for visible light into the biohybrid architecture and ensures the efficient wiring between the IO-TiO 2 electrode and the biocatalytic entity, PQQ-GDH provides the catalytic activity for the glucose oxidation and therefore feeds the light-driven reaction with electrons for an enhanced light-to-current conversion. Here, the IO-TiO 2 electrodes with pores of around 650 nm provide a suitable interface and morphology needed for the stable and functional assembly of polymer and enzyme. The IO-TiO 2 electrodes have been prepared by a template approach applying spin coating, allowing an easy scalability of the electrode height and surface area. The successful integration of the polymer and the enzyme is confirmed by the generation of an anodic photocurrent, showing an enhanced magnitude with increasing glucose concentrations. Compared to flat and nanostructured TiO 2 electrodes, the three-layered IO-TiO 2 electrodes give access to a 24-fold and 29-fold higher glucose-dependent photocurrent due to the higher polymer and enzyme loading in IO films. The three-dimensional IO-TiO 2 |PMSA1|PQQ-GDH architecture reaches maximum photocurrent densities of 44.7 ± 6.5 μA cm -2 at low potentials in the presence of glucose (for a three TiO 2 layer arrangement). The onset potential for the light-driven substrate oxidation is found to be at -0.315 V vs Ag/AgCl (1 M KCl) under illumination with 100 mW cm -2 , which is more negative than the redox potential of the enzyme. The results demonstrate the advantageous properties of IO-TiO 2 |PMSA1|PQQ-GDH biohybrid architectures for the light-driven glucose conversion with improved performance.

Viologen-modified electrodes for protection of hydrogenases from high potential inactivation while performing H2 oxidation at low overpotential.

PubMed

Oughli, Alaa A; Vélez, Marisela; Birrell, James A; Schuhmann, Wolfgang; Lubitz, Wolfgang; Plumeré, Nicolas; Rüdiger, Olaf

2018-06-08

In this work we present a viologen-modified electrode providing protection for hydrogenases against high potential inactivation. Hydrogenases, including O2-tolerant classes, suffer from reversible inactivation upon applying high potentials, which limits their use in biofuel cells to certain conditions. Our previously reported protection strategy based on the integration of hydrogenase into redox matrices enabled the use of these biocatalysts in biofuel cells even under anode limiting conditions. However, mediated catalysis required application of an overpotential to drive the reaction, and this translates into a power loss in a biofuel cell. In the present work, the enzyme is adsorbed on top of a covalently-attached viologen layer which leads to mixed, direct and mediated, electron transfer processes; at low overpotentials, the direct electron transfer process generates a catalytic current, while the mediated electron transfer through the viologens at higher potentials generates a redox buffer that prevents oxidative inactivation of the enzyme. Consequently, the enzyme starts the catalysis at no overpotential with viologen self-activated protection at high potentials.

Hydrogen peroxide biosensor based on microperoxidase-11 immobilized in a silica cavity array electrode.

PubMed

Tian, Shu; Zhou, Qun; Gu, Zhuomin; Gu, Xuefang; Zhao, Lili; Li, Yan; Zheng, Junwei

2013-03-30

Hydrogen peroxide biosensor based on the silica cavity array modified indium-doped tin oxide (ITO) electrode was constructed. An array of silica microcavities was fabricated by electrodeposition using the assembled polystyrene particles as template. Due to the resistance gradient of the silica cavity structure, the silica cavity exhibits a confinement effect on the electrochemical reactions, making the electrode function as an array of "soft" microelectrodes. The covalently immobilized microperoxidase-11(MP-11) inside these SiO2 cavities can keep its physiological activities, the electron transfer between the MP-11 and electrode was investigated through electrochemical method. The cyclic voltammetric curve shows a quasi-reversible electrochemical redox behavior with a pair of well-defined redox peaks, the cathodic and anodic peaks are located at -0.26 and -0.15V. Furthermore, the modified electrode exhibits high electrocatalytic activity toward the reduction of hydrogen peroxide and also shows good analytical performance for the amperometric detection of H2O2 with a linear range from 2×10(-6) to 6×10(-4)M. The good reproducibility and long-term stability of this novel electrode not only offer an opportunity for the detection of H2O2 in low concentration, but also provide a platform to construct various biosensors based on many other enzymes. Copyright © 2013 Elsevier B.V. All rights reserved.

Miniaturised enzymatic conductometric biosensor with Nafion membrane for the direct determination of formaldehyde in water samples.

PubMed

Nguyen-Boisse, Thanh-Thuy; Saulnier, Joëlle; Jaffrezic-Renault, Nicole; Lagarde, Florence

2014-02-01

A new conductometric enzyme-based biosensor was developed for the determination of formaldehyde (FA) in aqueous solutions. The biosensor was prepared by cross-linking formaldehyde dehydrogenase from Pseudomonas putida with bovine serum albumin in saturated glutaraldehyde vapours (GA) at the surface of interdigitated gold microelectrodes. Nicotinamide adenine dinucleotide cofactor (NAD(+)) was added in solution at each measurement to maintain enzyme activity. Addition of a Nafion layer over the enzyme modified electrode resulted in a significant increase of biosensor signal due to enhanced accumulation of protons generated by enzymatic reaction at the electrode surface. Different parameters affecting enzyme activity or playing a role in ionic transfer through the Nafion membrane were optimised. In optimal conditions (0.045 mg enzyme, 30 min exposure to GA, 0.3 μL of a 1% (v/v) Nafion solution deposit, measurement in 5 mM phosphate buffer pH 7 containing 20 μM NAD(+)), the biosensor signal was linear up to 10 mM FA, and the detection limit was 18 μM. Relative standard deviations calculated from five consecutive replicates of FA solutions were lower than 5% in the 1-10 mM range. The biosensor was successfully applied to the determination of FA in spiked water samples (tap water and Rhone river water), with recoveries in the 95-110% range.

Computational modeling of mediator oxidation by oxygen in an amperometric glucose biosensor.

PubMed

Simelevičius, Dainius; Petrauskas, Karolis; Baronas, Romas; Razumienė, Julija

2014-02-07

In this paper, an amperometric glucose biosensor is modeled numerically. The model is based on non-stationary reaction-diffusion type equations. The model consists of four layers. An enzyme layer lies directly on a working electrode surface. The enzyme layer is attached to an electrode by a polyvinyl alcohol (PVA) coated terylene membrane. This membrane is modeled as a PVA layer and a terylene layer, which have different diffusivities. The fourth layer of the model is the diffusion layer, which is modeled using the Nernst approach. The system of partial differential equations is solved numerically using the finite difference technique. The operation of the biosensor was analyzed computationally with special emphasis on the biosensor response sensitivity to oxygen when the experiment was carried out in aerobic conditions. Particularly, numerical experiments show that the overall biosensor response sensitivity to oxygen is insignificant. The simulation results qualitatively explain and confirm the experimentally observed biosensor behavior.

Computational Modeling of Mediator Oxidation by Oxygen in an Amperometric Glucose Biosensor

PubMed Central

Šimelevičius, Dainius; Petrauskas, Karolis; Baronas, Romas; Julija, Razumienė

2014-01-01

In this paper, an amperometric glucose biosensor is modeled numerically. The model is based on non-stationary reaction-diffusion type equations. The model consists of four layers. An enzyme layer lies directly on a working electrode surface. The enzyme layer is attached to an electrode by a polyvinyl alcohol (PVA) coated terylene membrane. This membrane is modeled as a PVA layer and a terylene layer, which have different diffusivities. The fourth layer of the model is the diffusion layer, which is modeled using the Nernst approach. The system of partial differential equations is solved numerically using the finite difference technique. The operation of the biosensor was analyzed computationally with special emphasis on the biosensor response sensitivity to oxygen when the experiment was carried out in aerobic conditions. Particularly, numerical experiments show that the overall biosensor response sensitivity to oxygen is insignificant. The simulation results qualitatively explain and confirm the experimentally observed biosensor behavior. PMID:24514882

An improved amperometric triglyceride biosensor based on co-immobilization of nanoparticles of lipase, glycerol kinase and glycerol 3-phosphate oxidase onto pencil graphite electrode.

PubMed

Narwal, Vinay; Pundir, C S

2017-05-01

Nanoparticles (NPs) of commercial lipase from Candida rugosa, of glycerol kinase (GK) from Cellulomonas species, of glycerol-3- phosphate oxidase (GPO) from Aerococcus viridans were prepared, characterized and co-immobilized onto a pencil graphite (PG) electrode. The morphological and electrochemical characterization of PG electrode was performed by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) before and after co-immobilization of enzyme nanoparticles (ENPs). An improved amperometric triglyceride (TG) biosensor was fabricated using Lipase NPs/GKNPs/GPONPs/PG electrode as the working electrode, Ag/AgCl as the standard electrode and Pt wire as auxiliary electrode. The biosensor showed optimum response within 2.5s at a pH 7.0 and temperature of 35°C. The biosensor measured current due to electrons generated at 0.1V against Ag/AgCl, from H 2 O 2 , which is produced from triolein by co-immobilized ENPs. A linear relationship was obtained over between a wide triolein concentration range (0.1mM-45mM) and current (mA) under optimal conditions. The Lipase NPs/GKNPs/GPONPs/PG electrode showed high sensitivity (1241±20mAcm -2 mM -1 ); a lower detection limit (0.1nM) and good correlation coeficient (R 2 =0.99) with a standard enzymic colorimetric method. Analytical recovery of added triolein in serum was 98.01%, within and between batch coefficients of variation (CV) were 0.05% and 0.06% respectively. The biosensor was evaluated and employed for determination of TG in the serum of apparently healthy subject and persons suffering from hypertriglyceridemia. The biosensor lost 20% of its initial activity after its continued uses over a period of 240days, while being stored at 4°C. Copyright © 2017 Elsevier Inc. All rights reserved.

A hybrid DNA-templated gold nanocluster for enhanced enzymatic reduction of oxygen

DOE PAGES

Chakraborty, Saumen; Babanova, Sofia; Rocha, Reginaldo C.; ...

2015-08-19

We report the synthesis and characterization of a new DNA-templated gold nanocluster (AuNC) of ~1 nm in diameter and possessing ~7 Au atoms. When integrated with bilirubin oxidase (BOD) and single walled carbon nanotubes (SWNTs), the AuNC acts as an enhancer of electron transfer (ET) and lowers the overpotential of electrocatalytic oxygen reduction reaction (ORR) by ~15 mV as compared to the enzyme alone. In addition, the presence of AuNC causes significant enhancements in the electrocatalytic current densities at the electrode. Control experiments show that such enhancement of ORR by the AuNC is specific to nanoclusters and not to plasmonicmore » gold particles. Rotating ring disk electrode (RRDE) measurements confirm 4e– reduction of O 2 to H 2O with minimal production of H 2O 2, suggesting that the presence of AuNC does not perturb the mechanism of ORR catalyzed by the enzyme. This unique role of the AuNC as enhancer of ET at the enzyme-electrode interface makes it a potential candidate for the development of cathodes in enzymatic fuel cells, which often suffer from poor electronic communication between the electrode surface and the enzyme active site. In conclusion, the AuNC displays phosphorescence with large Stokes shift and microsecond lifetime.« less

Bidirectional immobilization of affinity-tagged cytochrome c on electrode surfaces.

PubMed

Schröper, Florian; Baumann, Arnd; Offenhäusser, Andreas; Mayer, Dirk

2010-08-07

Here, we report a new strategy for the directed bivalent immobilization of cyt c on or between gold electrodes. C-terminal modification with cys- or his-tag did not affect the functional integrity of the protein. In combination with electrostatic protein binding, these tags enable a bifunctional immobilization between two electrodes or alternatively one electrode and interacting enzymes.

Magnetic Enzymatic Platform for Organophosphate Pesticide Detection Using Boron-doped Diamond Electrodes.

PubMed

Pino, Flavio; Ivandini, Tribidasari A; Nakata, Kazuya; Fujishima, Akira; Merkoçi, Arben; Einaga, Yasuaki

2015-01-01

A simple and reliable enzymatic system for organophosporus pesticide detection was successfully developed, by exploiting the synergy between the magnetic beads collection capacity and the outstanding electrochemistry property of boron-doped diamond electrodes. The determination of an organophosphate pesticide, chlorpyrifos (CPF), was performed based on the inhibition system of the enzyme acetylcholinesterase bonded to magnetic beads through a biotin-streptavidin complex system. A better sensitivity was found for a system with magnetic beads in the concentration range of 10(-9) to 10(-5) M. The estimated limits of detection based on IC10 (10% acetylcholinesterase (AChE) inhibition) have been detected and optimized to be 5.7 × 10(-10) M CPF. Spiked samples of water of Yokohama (Japan) have been measured to validate the efficiency of the enzymatic system. The results suggested that the use of magnetic beads to immobilize biomolecules or biosensing agents is suitable to maintain the superiority of BDD electrodes.

Preparation of Pt/polypyrrole-para toluene sulfonate hydrogen peroxide sensitive electrode for the utilizing as a biosensor.

PubMed

Çete, Servet; Bal, Özgür

2013-12-01

A film electrode with electropolymerization of pyrrole (Py) and para-toluene sulfonate (pTS) as a anionic dopant is prepared and its sensitivity to hydrogen peroxide is investigated. The polypyrrole is deposited on a 0.5 cm(2) Pt plate an electrochemically prepared pTS ion-doped polypyrrole film by scanning the electrode potential between - 0.8 and + 0.8 V at a scan rate of 20 mV/s. The electrode's sensitivity to hydrogen peroxide is investigated at room temperature using 0.1 M phosphate buffer at pH 7.5. The working potential is found as a 0.3 V. The concentrations of pyrrole and pTS are 50mM M and 25 mM. Polypyrrole was coated on the electrode surface within 10 cycles. İmmobilization of glucose oxidase carried out on Pt/polypyrrole-para toluene sulfonate (Pt/PPy-pTS) film by cross-linking with glutaraldehyde. The morphology of electrodes was characterized by SEM and AFM. Moreover, contact angle measurements were made with 1 μL water of polymer film and enzyme electrode. It has shown that enzyme electrode is very sensitive against to glucose.

Effect of enzymatic orientation through the use of syringaldazine molecules on multiple multi-copper oxidase enzymes.

PubMed

Ulyanova, Yevgenia; Babanova, Sofia; Pinchon, Erica; Matanovic, Ivana; Singhal, Sameer; Atanassov, Plamen

2014-07-14

The effect of proper enzyme orientation at the electrode surface was explored for two multi-copper oxygen reducing enzymes: Bilirubin Oxidase (BOx) and Laccase (Lac). Simultaneous utilization of "tethering" agent (1-pyrenebutanoic acid, succinimidyl ester; PBSE), for stable enzyme immobilization, and syringaldazine (Syr), for enzyme orientation, of both Lac and BOx led to a notable enhancement of the electrode performance. For Lac cathodes tested in solution it was established that PBSE-Lac and PBSE-Syr-Lac modified cathodes demonstrated approximately 6 and 9 times increase in current density, respectively, compared to physically adsorbed and randomly oriented Lac cathodes. Further testing in solution utilizing BOx showed an even higher increase in achievable current densities, thus BOx was chosen for additional testing in air-breathing mode. In subsequent air-breathing experiments the incorporation of PBSE and Syr with BOx resulted in current densities of 0.65 ± 0.1 mA cm(-2); 2.5 times higher when compared to an unmodified BOx cathode. A fully tethered/oriented BOx cathode was combined with a NAD-dependent Glucose Dehydrogenase anode for the fabrication of a complete enzymatic membraneless fuel cell. A maximum power of 1.03 ± 0.06 mW cm(-2) was recorded for the complete fuel cell. The observed significant enhancement in the performance of "oriented" cathodes was a result of proper enzyme orientation, leading to facilitated enzyme/electrode interface interactions.

An improved amperometric L-lactate biosensor based on covalent immobilization of microbial lactate oxidase onto carboxylated multiwalled carbon nanotubes/copper nanoparticles/polyaniline modified pencil graphite electrode.

PubMed

Dagar, Kusum; Pundir, C S

2017-01-01

An improved amperometric l-lactate biosensor was constructed based on covalent immobilization of lactate oxidase (LOx) from Pediococcus species onto carboxylated multiwalled carbon nanotubes (cMWCNT)/copper nanoparticles (CuNPs)/polyaniline (PANI) hybrid film electrodeposited on the surface of a pencil graphite electrode (PGE). The enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS), while CuNPs synthesized by chemical reduction method, were characterized by transmission electron microscopy (TEM), UV spectrascopy and X-ray diffraction (XRD). The biosensor showed maximum response within 5s at pH 8.0 in 0.05M sodium phosphate buffer and 37°C, when operated at 20mVs -1 . The biosensor had a detection limit of 0.25μM with a wide working range between 1μM-2500μM. The biosensor was employed for measurement of l-lactic acid level in plasma of apparently healthy and diseased persons. Analytical recovery of added lactic acid in plasma was 95.5%. Within- and between-batch coefficients of variations were 6.24% and 4.19% respectively. There was a good correlation (R 2 =0.97) between plasma lactate values as measured by standard enzymatic spectrophotometric method and the present biosensor. The working enzyme electrode was used 180 times over a period of 140 days, when stored at 4°C. Copyright © 2016. Published by Elsevier Inc.

Construction of ferrocene modified conducting polymer based amperometric urea biosensor.

PubMed

Dervisevic, Muamer; Dervisevic, Esma; Senel, Mehmet; Cevik, Emre; Yildiz, Huseyin Bekir; Camurlu, Pınar

2017-07-01

Herein, an electrochemical urea sensing bio-electrode is reported that has been constructed by firstly electropolymerizing 4-(2,5-Di(thiophen-2-yl)-1H-pyrrol-1-yl)aniline monomer (SNS-Aniline) on Pencil Graphite Electrode (PGE), then modifying the polymer coated electrode surface with di-amino-Ferrocene (DAFc) as the mediator, and lastly Urease enzyme through glutaraldehyde crosslinking. The effect of pH, temperature, polymer thickness, and applied potential on the electrode current response was investigated besides performing storage and operational stability experiments with the interference studies. The resulting urea biosensor's amperometric response was linear in the range of 0.1-8.5mM with the sensitivity of 0.54μA/mM, detection limit of 12μM, and short response time of 2s. The designed bio-electrode was tested with real human blood and urine samples where it showed excellent analytical performance with insignificant interference. Copyright © 2017 Elsevier Inc. All rights reserved.

Fabrication and characterization of spiral interdigitated electrodes based biosensor for salivary glucose detection

NASA Astrophysics Data System (ADS)

Adelyn, P. Y. P.; Hashim, U.; Arshad, M. K. Md; Voon, C. H.; Liu, Wei-Wen; Kahar, S. M.; Huda, A. R. N.; Lee, H. Cheun

2017-03-01

This work introduces the non-invasive glucose monitoring technique by using the Complementary Metal Oxide Semiconductor (CMOS) technologically fabricated spiral Interdigitated Electrodes (IDE) based biosensor. Scanning Electron Microscopy (SEM) image explores the morphology of spiral IDE while Energy Dispersive X-Ray (EDX) determines the elements induced in spiral IDE. Oral saliva of two patients are collected and tested on the spiral IDE sensor with electrical characterization as glucose detection results. However, both patients exhibit their glucose level characteristics inconsistently. Therefore, this work could be extended and enhanced by adding Glutaraldehyde in between 3-Aminoproply)triethoxysilane (APTES) modified and glucose oxidase (GOD) enzyme immobilized layer with FTIR validation for bonding attachment.

Enzyme electrode for on-line determination of ethanol and methanol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belghith, H.; Romette, J.; Thomas, D.

Since a stable alcohol oxidase with a high specific activity is not commercially available, they propose to produce and purify this enzyme from a strain of the yeast Hansenula polymorpha. This alcohol oxidase was immobilized into a gelatin matrix and its activity was estimated by a pO/sub 2/ sensor. The enzyme electrode obtained was then used in a continuous flow system to measure methanol or ethanol concentrations. The sample oxygen content dependence of the signal was minimized by the support properties. Measuring time for each sample were less than two minutes including response data treatment and rinsing step. The enzymemore » electrode response was set for ethanol from 0.5 mM to 15 mM and for methanol from 10 mM to 300 mM. On repeated use, the electrode signal for 10 mM of ethanol was stable for at least 500 assays. Analysis have been performed in different beverages such as wine and beer, and the results compared to those obtained with classical methods of analysis.« less

Stack air-breathing membraneless glucose microfluidic biofuel cell

NASA Astrophysics Data System (ADS)

Galindo-de-la-Rosa, J.; Moreno-Zuria, A.; Vallejo-Becerra, V.; Arjona, N.; Guerra-Balcázar, M.; Ledesma-García, J.; Arriaga, L. G.

2016-11-01

A novel stacked microfluidic fuel cell design comprising re-utilization of the anodic and cathodic solutions on the secondary cell is presented. This membraneless microfluidic fuel cell employs porous flow-through electrodes in a “V”-shape cell architecture. Enzymatic bioanodic arrays based on glucose oxidase were prepared by immobilizing the enzyme onto Toray carbon paper electrodes using tetrabutylammonium bromide, Nafion and glutaraldehyde. These electrodes were characterized through the scanning electrochemical microscope technique, evidencing a good electrochemical response due to the electronic transference observed with the presence of glucose over the entire of the electrode. Moreover, the evaluation of this microfluidic fuel cell with an air-breathing system in a double-cell mode showed a performance of 0.8951 mWcm-2 in a series connection (2.2822mAcm-2, 1.3607V), and 0.8427 mWcm-2 in a parallel connection (3.5786mAcm-2, 0.8164V).

Hybrid biobattery based on arylated carbon nanotubes and laccase.

PubMed

Stolarczyk, Krzysztof; Sepelowska, Małgorzata; Lyp, Dominika; Zelechowska, Kamila; Biernat, Jan F; Rogalski, Jerzy; Farmer, Kevin D; Roberts, Ken N; Bilewicz, Renata

2012-10-01

Single-walled carbon nanotubes (SWCNT) were covalently modified with anthracene and anthraquinone and used for the construction of cathodes for biocatalytic reduction of dioxygen. The nanotubes with aromatic groups casted onto the electrode increased the working surface of the electrode and enabled efficient direct electron transfer (DET) between the enzyme and the electrode. The aryl groups enter the hydrophobic pocket of the T1 center of laccase responsible for exchanging electrons with the substrate. Glassy carbon electrode covered with arylated SWCNT and coated with a layer of neutralized Nafion containing laccase was found to be a very efficient cathode in the hybrid battery. Zn wire covered with a Nafion film served as the anode. The cell parameters were determined: power density was 2 mW/cm(2) and the open circuit potential was 1.5 V. Copyright © 2011 Elsevier B.V. All rights reserved.

Determination of Penicillin Using an Immobilized Enzyme Electrode: An Undergraduate Experiment.

ERIC Educational Resources Information Center

Mifflin, Theodore E.; And Others

1984-01-01

Background information, procedures, and results are provided for an experiment in which students: (1) construct an immobilized penicillinase electrode; (2) evaluate electron response as a function of penicillin concentration; and (3) study effects of solvent compositions, ionic strength, and equilibrium time upon electrode response. (JN)

Electrochemical biosensor based on glucose oxidase encapsulated within enzymatically synthesized poly(1,10-phenanthroline-5,6-dione).

PubMed

Ciftci, Hakan; Oztekin, Yasemin; Tamer, Ugur; Ramanaviciene, Almira; Ramanavicius, Arunas

2014-11-01

This study is focused on the investigation of electrocatalytic effect of glucose oxidase (GOx) immobilized on the graphite rod (GR) electrode. The enzyme modified electrode was prepared by encapsulation of immobilized GOx within enzymatically formed poly(1,10-phenanthroline-5,6-dione) (pPD) film. The electrochemical responses of such enzymatic electrode (pPD/GOx/GR) vs. different glucose concentrations were examined chronoamperometrically in acetate-phosphate buffer solution (A-PBS), pH 6.0, under aerobic or anaerobic conditions. Amperometric signals of the pPD/GOx/GR electrode exhibited well-defined hyperbolic dependence upon glucose concentration. Amperometric signals at 100mM of glucose were 41.17 and 32.27 μA under aerobic and anaerobic conditions, respectively. Amperometric signals of the pPD/GOx/GR electrode decreased by 6% within seven days. The pPD/GOx/GR electrode showed excellent selectivity in the presence of dopamine and uric acid. Furthermore it had a good reproducibility and repeatability with standard deviation of 9.4% and 8.0%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

Redox polymer and probe DNA tethered to gold electrodes for enzyme-amplified amperometric detection of DNA hybridization.

PubMed

Kavanagh, Paul; Leech, Dónal

2006-04-15

The detection of nucleic acids based upon recognition surfaces formed by co-immobilization of a redox polymer mediator and DNA probe sequences on gold electrodes is described. The recognition surface consists of a redox polymer, [Os(2,2'-bipyridine)2(polyvinylimidazole)(10)Cl](+/2+), and a model single DNA strand cross-linked and tethered to a gold electrode via an anchoring self-assembled monolayer (SAM) of cysteamine. Hybridization between the immobilized probe DNA of the recognition surface and a biotin-conjugated target DNA sequence (designed from the ssrA gene of Listeria monocytogenes), followed by addition of an enzyme (glucose oxidase)-avidin conjugate, results in electrical contact between the enzyme and the mediating redox polymer. In the presence of glucose, the current generated due to the catalytic oxidation of glucose to gluconolactone is measured, and a response is obtained that is binding-dependent. The tethering of the probe DNA and redox polymer to the SAM improves the stability of the surface to assay conditions of rigorous washing and high salt concentration (1 M). These conditions eliminate nonspecific interaction of both the target DNA and the enzyme-avidin conjugate with the recognition surfaces. The sensor response increases linearly with increasing concentration of target DNA in the range of 1 x 10(-9) to 2 x 10(-6) M. The detection limit is approximately 1.4 fmol, (corresponding to 0.2 nM of target DNA). Regeneration of the recognition surface is possible by treatment with 0.25 M NaOH solution. After rehybridization of the regenerated surface with the target DNA sequence, >95% of the current is recovered, indicating that the redox polymer and probe DNA are strongly bound to the surface. These results demonstrate the utility of the proposed approach.

Au nanoparticles/hollow molybdenum disulfide microcubes based biosensor for microRNA-21 detection coupled with duplex-specific nuclease and enzyme signal amplification.

PubMed

Shuai, Hong-Lei; Huang, Ke-Jing; Chen, Ying-Xu; Fang, Lin-Xia; Jia, Meng-Pei

2017-03-15

An ultrasensitive electrochemical biosensor for detecting microRNAs is fabricated based on hollow molybdenum disulfide (MoS 2 ) microcubes. Duplex-specific nuclease, enzyme and electrochemical-chemical-chemical redox cycling are used for signal amplification. Hollow MoS 2 microcubes constructed by ultrathin nanosheets are synthesized by a facile template-assisted strategy and used as supporting substrate. For biosensor assembling, biotinylated ssDNA capture probes are first immobilized on Au nanoparticles (AuNPs)/MoS 2 modified electrode in order to combine with streptavidin-conjugated alkaline phosphatase (SA-ALP). When capture probes hybridize with miRNAs, duplex-specific nuclease cleaves the formative duplexes. At the moment, the biotin group strips from the electrode surface and SA-ALP is incapacitated to attach onto electrode. Then, ascorbic acids induce the electrochemical-chemical-chemical redox cycling to produce electrochemical response in the presence of ferrocene methanol and tris (2-carboxyethyl) phosphine. Under optimum conditions, the proposed biosensor shows a good linear relationship between the current variation and logarithm of the microRNAs concentration ranging from 0.1fM to 0.1pM with a detection limit of 0.086fM (S/N=3). Furthermore, the biosensor is successfully applied to detect target miRNA-21 in human serum samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Fully Enzymatic Membraneless Glucose|Oxygen Fuel Cell That Provides 0.275 mA cm(-2) in 5 mM Glucose, Operates in Human Physiological Solutions, and Powers Transmission of Sensing Data.

PubMed

Ó Conghaile, Peter; Falk, Magnus; MacAodha, Domhnall; Yakovleva, Maria E; Gonaus, Christoph; Peterbauer, Clemens K; Gorton, Lo; Shleev, Sergey; Leech, Dónal

2016-02-16

Coimmobilization of pyranose dehydrogenase as an enzyme catalyst, osmium redox polymers [Os(4,4'-dimethoxy-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) or [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) as mediators, and carbon nanotube conductive scaffolds in films on graphite electrodes provides enzyme electrodes for glucose oxidation. The recombinant enzyme and a deglycosylated form, both expressed in Pichia pastoris, are investigated and compared as biocatalysts for glucose oxidation using flow injection amperometry and voltammetry. In the presence of 5 mM glucose in phosphate-buffered saline (PBS) (50 mM phosphate buffer solution, pH 7.4, with 150 mM NaCl), higher glucose oxidation current densities, 0.41 mA cm(-2), are obtained from enzyme electrodes containing the deglycosylated form of the enzyme. The optimized glucose-oxidizing anode, prepared using deglycosylated enzyme coimmobilized with [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) and carbon nanotubes, was coupled with an oxygen-reducing bilirubin oxidase on gold nanoparticle dispersed on gold electrode as a biocathode to provide a membraneless fully enzymatic fuel cell. A maximum power density of 275 μW cm(-2) is obtained in 5 mM glucose in PBS, the highest to date under these conditions, providing sufficient power to enable wireless transmission of a signal to a data logger. When tested in whole human blood and unstimulated human saliva maximum power densities of 73 and 6 μW cm(-2) are obtained for the same fuel cell configuration, respectively.

Amperometric Biosensor Based on Diamine Oxidase/Platinum Nanoparticles/Graphene/Chitosan Modified Screen-Printed Carbon Electrode for Histamine Detection.

PubMed

Apetrei, Irina Mirela; Apetrei, Constantin

2016-03-24

This work describes the development and optimization studies of a novel biosensor employed in the detection and quantification of histamine in freshwater fish samples. The proposed biosensor is based on a modified carbon screen-printed electrode with diamineoxidase, graphene and platinum nanoparticles, which detects the hydrogen peroxide formed by the chemical process biocatalysed by the enzyme diamine oxidase and immobilized onto the nanostructurated surface of the receptor element. The amperometric measurements with the biosensor have been implemented in buffer solution of pH 7.4, applying an optimal low potential of +0.4 V. The novel biosensor shows high sensitivity (0.0631 μA·μM), low detection limit (2.54 × 10(-8) M) and a broad linear domain from 0.1 to 300 μM. The applicability in natural complex samples and the analytical parameters of this enzyme sensor have been performed in the quantification of histamine in freshwater fish. An excellent correlation among results achieved with the developed biosensor and results found with the standard method for all freshwater fish samples has been achieved.

Amperometric Biosensor Based on Diamine Oxidase/Platinum Nanoparticles/Graphene/Chitosan Modified Screen-Printed Carbon Electrode for Histamine Detection

PubMed Central

Apetrei, Irina Mirela; Apetrei, Constantin

2016-01-01

This work describes the development and optimization studies of a novel biosensor employed in the detection and quantification of histamine in freshwater fish samples. The proposed biosensor is based on a modified carbon screen-printed electrode with diamineoxidase, graphene and platinum nanoparticles, which detects the hydrogen peroxide formed by the chemical process biocatalysed by the enzyme diamine oxidase and immobilized onto the nanostructurated surface of the receptor element. The amperometric measurements with the biosensor have been implemented in buffer solution of pH 7.4, applying an optimal low potential of +0.4 V. The novel biosensor shows high sensitivity (0.0631 μA·μM), low detection limit (2.54 × 10−8 M) and a broad linear domain from 0.1 to 300 μM. The applicability in natural complex samples and the analytical parameters of this enzyme sensor have been performed in the quantification of histamine in freshwater fish. An excellent correlation among results achieved with the developed biosensor and results found with the standard method for all freshwater fish samples has been achieved. PMID:27023541

How light-harvesting semiconductors can alter the bias of reversible electrocatalysts in favor of H2 production and CO2 reduction.

PubMed

Bachmeier, Andreas; Wang, Vincent C C; Woolerton, Thomas W; Bell, Sophie; Fontecilla-Camps, Juan C; Can, Mehmet; Ragsdale, Stephen W; Chaudhary, Yatendra S; Armstrong, Fraser A

2013-10-09

The most efficient catalysts for solar fuel production should operate close to reversible potentials, yet possess a bias for the fuel-forming direction. Protein film electrochemical studies of Ni-containing carbon monoxide dehydrogenase and [NiFeSe]-hydrogenase, each a reversible electrocatalyst, show that the electronic state of the electrode strongly biases the direction of electrocatalysis of CO2/CO and H(+)/H2 interconversions. Attached to graphite electrodes, these enzymes show high activities for both oxidation and reduction, but there is a marked shift in bias, in favor of CO2 or H(+) reduction, when the respective enzymes are attached instead to n-type semiconductor electrodes constructed from CdS and TiO2 nanoparticles. This catalytic rectification effect can arise for a reversible electrocatalyst attached to a semiconductor electrode if the electrode transforms between semiconductor- and metallic-like behavior across the same narrow potential range (<0.25 V) that the electrocatalytic current switches between oxidation and reduction.

Direct metabolite detection with an n-type accumulation mode organic electrochemical transistor

PubMed Central

Maria, Iuliana Petruta; Uguz, Ilke

2018-01-01

The inherent specificity and electrochemical reversibility of enzymes poise them as the biorecognition element of choice for a wide range of metabolites. To use enzymes efficiently in biosensors, the redox centers of the protein should have good electrical communication with the transducing electrode, which requires either the use of mediators or tedious biofunctionalization approaches. We report an all-polymer micrometer-scale transistor platform for the detection of lactate, a significant metabolite in cellular metabolic pathways associated with critical health care conditions. The device embodies a new concept in metabolite sensing where we take advantage of the ion-to-electron transducing qualities of an electron-transporting (n-type) organic semiconductor and the inherent amplification properties of an ion-to-electron converting device, the organic electrochemical transistor. The n-type polymer incorporates hydrophilic side chains to enhance ion transport/injection, as well as to facilitate enzyme conjugation. The material is capable of accepting electrons of the enzymatic reaction and acts as a series of redox centers capable of switching between the neutral and reduced state. The result is a fast, selective, and sensitive metabolite sensor. The advantage of this device compared to traditional amperometric sensors is the amplification of the input signal endowed by the electrochemical transistor circuit and the design simplicity obviating the need for a reference electrode. The combination of redox enzymes and electron-transporting polymers will open up an avenue not only for the field of biosensors but also for the development of enzyme-based electrocatalytic energy generation/storage devices.

Direct metabolite detection with an n-type accumulation mode organic electrochemical transistor.

PubMed

Pappa, Anna Maria; Ohayon, David; Giovannitti, Alexander; Maria, Iuliana Petruta; Savva, Achilleas; Uguz, Ilke; Rivnay, Jonathan; McCulloch, Iain; Owens, Róisín M; Inal, Sahika

2018-06-01

The inherent specificity and electrochemical reversibility of enzymes poise them as the biorecognition element of choice for a wide range of metabolites. To use enzymes efficiently in biosensors, the redox centers of the protein should have good electrical communication with the transducing electrode, which requires either the use of mediators or tedious biofunctionalization approaches. We report an all-polymer micrometer-scale transistor platform for the detection of lactate, a significant metabolite in cellular metabolic pathways associated with critical health care conditions. The device embodies a new concept in metabolite sensing where we take advantage of the ion-to-electron transducing qualities of an electron-transporting (n-type) organic semiconductor and the inherent amplification properties of an ion-to-electron converting device, the organic electrochemical transistor. The n-type polymer incorporates hydrophilic side chains to enhance ion transport/injection, as well as to facilitate enzyme conjugation. The material is capable of accepting electrons of the enzymatic reaction and acts as a series of redox centers capable of switching between the neutral and reduced state. The result is a fast, selective, and sensitive metabolite sensor. The advantage of this device compared to traditional amperometric sensors is the amplification of the input signal endowed by the electrochemical transistor circuit and the design simplicity obviating the need for a reference electrode. The combination of redox enzymes and electron-transporting polymers will open up an avenue not only for the field of biosensors but also for the development of enzyme-based electrocatalytic energy generation/storage devices.

Development of a screen-printed carbon electrode based disposable enzyme sensor strip for the measurement of glycated albumin.

PubMed

Hatada, Mika; Tsugawa, Wakako; Kamio, Eri; Loew, Noya; Klonoff, David C; Sode, Koji

2017-02-15

Glycated proteins, such as glycated hemoglobin (HbA1c) or glycated albumin (GA) in the blood, are essential indicators of glycemic control for diabetes mellitus. Since GA, compared to HbA1c, is more sensitive to short term changes in glycemic levels, GA is expected to be used as an alternative or together with HbA1c as a surrogate marker indicator for glycemic control. In this paper we report the development of a sensing system for measuring GA by combining an enzyme analysis method, which is already used in clinical practice, with electrochemical principles. We used fructosyl amino acid oxidase, hexaammineruthenium(III) chloride as the electron mediator, and an inexpensive and economically attractive screen-printed carbon electrode. We used chronoamperometry to measure protease-digested GA samples. The developed sensor strips were able to measure protease-digested samples containing GA in very small sample volumes (1.3μL) within about 1min. We also prepared enzyme sensor strips suitable for clinical use in which the enzyme and the mediator were deposited and dried on. This sensor system showed a clear correlation between the GA concentration and the resulting current. The strips were stable following 3 months of storage at 37°C. We conclude that this disposable enzyme sensor strip system for measuring GA is suitable for point-of-care test (POCT) applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Printed Graphene Electrochemical Biosensors Fabricated by Inkjet Maskless Lithography for Rapid and Sensitive Detection of Organophosphates.

PubMed

Hondred, John A; Breger, Joyce C; Alves, Nathan J; Trammell, Scott A; Walper, Scott A; Medintz, Igor L; Claussen, Jonathan C

2018-04-04

Solution phase printing of graphene-based electrodes has recently become an attractive low-cost, scalable manufacturing technique to create in-field electrochemical biosensors. Here, we report a graphene-based electrode developed via inkjet maskless lithography (IML) for the direct and rapid monitoring of triple-O linked phosphonate organophosphates (OPs); these constitute the active compounds found in chemical warfare agents and pesticides that exhibit acute toxicity as well as long-term pollution to soils and waterways. The IML-printed graphene electrode is nano/microstructured with a 1000 mW benchtop laser engraver and electrochemically deposited platinum nanoparticles (dia. ∼25 nm) to improve its electrical conductivity (sheet resistance decreased from ∼10 000 to 100 Ω/sq), surface area, and electroactive nature for subsequent enzyme functionalization and biosensing. The enzyme phosphotriesterase (PTE) was conjugated to the electrode surface via glutaraldehyde cross-linking. The resulting biosensor was able to rapidly measure (5 s response time) the insecticide paraoxon (a model OP) with a low detection limit (3 nM), and high sensitivity (370 nA/μM) with negligible interference from similar nerve agents. Moreover, the biosensor exhibited high reusability (average of 0.3% decrease in sensitivity per sensing event), stability (90% anodic current signal retention over 1000 s), longevity (70% retained sensitivity after 8 weeks), and the ability to selectively sense OP in actual soil and water samples. Hence, this work presents a scalable printed graphene manufacturing technique that can be used to create OP biosensors that are suitable for in-field applications as well as, more generally, for low-cost biosensor test strips that could be incorporated into wearable or disposable sensing paradigms.

Polymeric mercaptosilane-modified platinum electrodes for elimination of interferants in glucose biosensors.

PubMed

Jung, S K; Wilson, G S

1996-02-15

An oxidase-based glucose sensor has been developed that uses a mercaptosilane-modified platinum electrode to achieve selectivity of electrochemical interferants. A platinum-iridium (9:1) wire (0.178 mm o.d., sensing area of 1.12 mm2) is modified with (3-mercaptopropyl)trimethoxysilane. The modified sensors show excellent operational stability for more than 5 days. Glucose oxidase is immobilized on the modified surface (i) by using 3-maleimidopropionic acid as a linker or (ii) by cross-liking with bovine serum albumin using glutaraldehyde. Sensitivities in the range of 9.97 nA/mM glucose are observed when the enzyme is immobilized by method ii. Lower sensitivities (1.13 x 10(-1) nA/mM glucose) are observed when immobilization method i is employed. In terms of linear response range, the sensor enzyme-immobilized by method i is superior to that immobilized by method ii. The linearity is improved upon coating the enzyme layer with polyurethane. The sensor immobilized by method ii and coated with polyurethane exhibits a linear range to 15 mM glucose and excellent selectivity to glucose (0.47 nA/mM) against interferants such as ascorbic acid, uric acid, and acetaminophen.

Performance of non-compartmentalized enzymatic biofuel cell based on buckypaper cathode and ferrocene-containing redox polymer anode

NASA Astrophysics Data System (ADS)

Bunte, Christine; Hussein, Laith; Urban, Gerald A.

2014-02-01

Novel single compartment Glucose/O2 biofuel cells (BFCs) were developed using immobilized enzymes and the mediated electron transfer (MET) approach. The bioanode was prepared through a ferrocene-containing redox polymer crosslinked in the presence of a biocatalyst on a glassy carbon support. Here, the redox polymer can physically entrap the enzyme and prevent it from leaching. Additionally it provides a biocompatible microenvironment and thus could extend the life time of enzyme. On the other side, the mediated biocathode was prepared based on bilirubin oxidase and 2,2‧-azinobis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS2-) system which has been physically entrapped in Nafion matrix and then adsorbed directly on a highly porous, conductive and functionalized buckypaper (fBP). Both electrodes were characterized physically and electrochemically. Employing these electrodes, the resulting BFC generates an open circuit voltage (Voc) of approximately 0.550 V and a peak power density of 26 μW cm-2 at 0.2 V at 37 °C in quiescent O2-saturated physiological buffer containing 5 mM glucose. The cell sustains a load up to 225 μA cm-2. Moreover, a high short circuit current (Isc) of 300 μA cm-2 is approached. This BFC can operate in mild conditions without using any toxic materials which makes it attractive for implantable devices.

Construction and Characterization of a Chitosan-Immobilized-Enzyme and β-Cyclodextrin-Included-Ferrocene-Based Electrochemical Biosensor for H₂O₂ Detection.

PubMed

Dong, Wenbo; Wang, Kaiyin; Chen, Yu; Li, Weiping; Ye, Yanchun; Jin, Shaohua

2017-07-28

An electrochemical detection biosensor was prepared with the chitosan-immobilized-enzyme (CTS-CAT) and β-cyclodextrin-included-ferrocene (β-CD-FE) complex for the determination of H₂O₂. Ferrocene (FE) was included in β-cyclodextrin (β-CD) to increase its stability. The structure of the β-CD-FE was characterized. The inclusion amount, inclusion rate, and electrochemical properties of inclusion complexes were determined to optimize the reaction conditions for the inclusion. CTS-CAT was prepared by a step-by-step immobilization method, which overcame the disadvantages of the conventional preparation methods. The immobilization conditions were optimized to obtain the desired enzyme activity. CTS-CAT/β-CD-FE composite electrodes were prepared by compositing the CTS-CAT with the β-CD-FE complex on a glassy carbon electrode and used for the electrochemical detection of H₂O₂. It was found that the CTS-CAT could produce a strong reduction peak current in response to H₂O₂ and the β-CD-FE could amplify the current signal. The peak current exhibited a linear relationship with the H₂O₂ concentration in the range of 1.0 × 10 -7 -6.0 × 10 -3 mol/L. Our work provided a novel method for the construction of electrochemical biosensors with a fast response, good stability, high sensitivity, and a wide linear response range based on the composite of chitosan and cyclodextrin.

Utilization of Diamine Oxidase Enzyme from Mung Bean Sprouts (Vigna radiata L) for Histamine biosensors

NASA Astrophysics Data System (ADS)

Karim, Abdul; Wahab, A. W.; Raya, I.; Natsir, H.; Arif, A. R.

2018-03-01

This research is aimed to utilize the diamine oxidase enzyme (DAO) which isolated from mung bean sprouts (Vigna radiata L) to develop histamine biosensors based on electode enzyme with the amperometric method (cyclic voltammetry).The DAO enzyme is trapped inside the membrane of chitin-cellulose acetate 2:1 and glutaraldehyde which super imposed on a Pt electrode. Histamine will be oxidized by DAO enzyme to produce aldehydes and H2O2 that acting as electron transfer mediators.The performance of biosensors will be measured at various concentrations of glutaraldehyde, temperature changes and different range of pH. Recently, it has been found that the optimal conditions obtained from the paramaters as follows; at 25% of glutaraldehyde, temperature of 37°C and pH of 7.4. Eventually, the results provided an expectation for applying histamine biosensors in determining the freshness and safety of fish specifically skombroidae families.

Direct enzymatic bioelectrocatalysis: differentiating between myth and reality

PubMed Central

2017-01-01

Enzymatic bioelectrocatalysis is being increasingly exploited to better understand oxidoreductase enzymes, to develop minimalistic yet specific biosensor platforms, and to develop alternative energy conversion devices and bioelectrosynthetic devices for the production of energy and/or important chemical commodities. In some cases, these enzymes are able to electronically communicate with an appropriately designed electrode surface without the requirement of an electron mediator to shuttle electrons between the enzyme and electrode. This phenomenon has been termed direct electron transfer or direct bioelectrocatalysis. While many thorough studies have extensively investigated this fascinating feat, it is sometimes difficult to differentiate desirable enzymatic bioelectrocatalysis from electrocatalysis deriving from inactivated enzyme that may have also released its catalytic cofactor. This article will review direct bioelectrocatalysis of several oxidoreductases, with an emphasis on experiments that provide support for direct bioelectrocatalysis versus denatured enzyme or dissociated cofactor. Finally, this review will conclude with a series of proposed control experiments that could be adopted to discern successful direct electronic communication of an enzyme from its denatured counterpart. PMID:28637918

Versatile multi-functionalization of protein nanofibrils for biosensor applications

NASA Astrophysics Data System (ADS)

Sasso, L.; Suei, S.; Domigan, L.; Healy, J.; Nock, V.; Williams, M. A. K.; Gerrard, J. A.

2014-01-01

Protein nanofibrils offer advantages over other nanostructures due to the ease in their self-assembly and the versatility of surface chemistry available. Yet, an efficient and general methodology for their post-assembly functionalization remains a significant challenge. We introduce a generic approach, based on biotinylation and thiolation, for the multi-functionalization of protein nanofibrils self-assembled from whey proteins. Biochemical characterization shows the effects of the functionalization onto the nanofibrils' surface, giving insights into the changes in surface chemistry of the nanostructures. We show how these methods can be used to decorate whey protein nanofibrils with several components such as fluorescent quantum dots, enzymes, and metal nanoparticles. A multi-functionalization approach is used, as a proof of principle, for the development of a glucose biosensor platform, where the protein nanofibrils act as nanoscaffolds for glucose oxidase. Biotinylation is used for enzyme attachment and thiolation for nanoscaffold anchoring onto a gold electrode surface. Characterization via cyclic voltammetry shows an increase in glucose-oxidase mediated current response due to thiol-metal interactions with the gold electrode. The presented approach for protein nanofibril multi-functionalization is novel and has the potential of being applied to other protein nanostructures with similar surface chemistry.Protein nanofibrils offer advantages over other nanostructures due to the ease in their self-assembly and the versatility of surface chemistry available. Yet, an efficient and general methodology for their post-assembly functionalization remains a significant challenge. We introduce a generic approach, based on biotinylation and thiolation, for the multi-functionalization of protein nanofibrils self-assembled from whey proteins. Biochemical characterization shows the effects of the functionalization onto the nanofibrils' surface, giving insights into the changes in surface chemistry of the nanostructures. We show how these methods can be used to decorate whey protein nanofibrils with several components such as fluorescent quantum dots, enzymes, and metal nanoparticles. A multi-functionalization approach is used, as a proof of principle, for the development of a glucose biosensor platform, where the protein nanofibrils act as nanoscaffolds for glucose oxidase. Biotinylation is used for enzyme attachment and thiolation for nanoscaffold anchoring onto a gold electrode surface. Characterization via cyclic voltammetry shows an increase in glucose-oxidase mediated current response due to thiol-metal interactions with the gold electrode. The presented approach for protein nanofibril multi-functionalization is novel and has the potential of being applied to other protein nanostructures with similar surface chemistry. Electronic supplementary information (ESI) available: Cyclic voltammetry characterization of biosensor platforms including bare Au electrodes (Fig. S1), biosensor response to various glucose concentrations (Fig. S2), and AFM roughness measurements due to WPNF modifications (Fig. S3). See DOI: 10.1039/c3nr05752f

The electrochemical behavior of a FAD dependent glucose dehydrogenase with direct electron transfer subunit by immobilization on self-assembled monolayers.

PubMed

Lee, Inyoung; Loew, Noya; Tsugawa, Wakako; Lin, Chi-En; Probst, David; La Belle, Jeffrey T; Sode, Koji

2018-06-01

Continuous glucose monitoring (CGM) is a vital technology for diabetes patients by providing tight glycemic control. Currently, many commercially available CGM sensors use glucose oxidase (GOD) as sensor element, but this enzyme is not able to transfer electrons directly to the electrode without oxygen or an electronic mediator. We previously reported a mutated FAD dependent glucose dehydrogenase complex (FADGDH) capable of direct electron transfer (DET) via an electron transfer subunit without involving oxygen or a mediator. In this study, we investigated the electrochemical response of DET by controlling the immobilization of DET-FADGDH using 3 types of self-assembled monolayers (SAMs) with varying lengths. With the employment of DET-FADGDH and SAM, high current densities were achieved without being affected by interfering substances such as acetaminophen and ascorbic acid. Additionally, the current generated from DET-FADGDH electrodes decreased with increasing length of SAM, suggesting that the DET ability can be affected by the distance between the enzyme and the electrode. These results indicate the feasibility of controlling the immobilization state of the enzymes on the electrode surface. Copyright © 2017. Published by Elsevier B.V.

Ready to use bioinformatics analysis as a tool to predict immobilisation strategies for protein direct electron transfer (DET).

PubMed

Cazelles, R; Lalaoui, N; Hartmann, T; Leimkühler, S; Wollenberger, U; Antonietti, M; Cosnier, S

2016-11-15

Direct electron transfer (DET) to proteins is of considerable interest for the development of biosensors and bioelectrocatalysts. While protein structure is mainly used as a method of attaching the protein to the electrode surface, we employed bioinformatics analysis to predict the suitable orientation of the enzymes to promote DET. Structure similarity and secondary structure prediction were combined underlying localized amino-acids able to direct one of the enzyme's electron relays toward the electrode surface by creating a suitable bioelectrocatalytic nanostructure. The electro-polymerization of pyrene pyrrole onto a fluorine-doped tin oxide (FTO) electrode allowed the targeted orientation of the formate dehydrogenase enzyme from Rhodobacter capsulatus (RcFDH) by means of hydrophobic interactions. Its electron relays were directed to the FTO surface, thus promoting DET. The reduction of nicotinamide adenine dinucleotide (NAD(+)) generating a maximum current density of 1μAcm(-2) with 10mM NAD(+) leads to a turnover number of 0.09electron/s/molRcFDH. This work represents a practical approach to evaluate electrode surface modification strategies in order to create valuable bioelectrocatalysts. Copyright © 2016 Elsevier B.V. All rights reserved.

Redox polymer mediation for enzymatic biofuel cells

NASA Astrophysics Data System (ADS)

Gallaway, Joshua

Mediated biocatalytic cathodes prepared from the oxygen-reducing enzyme laccase and redox-conducting osmium hydrogels were characterized for use as cathodes in enzymatic biofuel cells. A series of osmium-based redox polymers was synthesized with redox potentials spanning the range from 0.11 V to 0.85 V (SHE), and the resulting biocatalytic electrodes were modeled to determine reaction kinetic constants using the current response, measured osmium concentration, and measured apparent electron diffusion. As in solution-phase systems, the bimolecular rate constant for mediation was found to vary greatly with mediator potential---from 250 s-1M-1 when mediator and enzyme were close in potential to 9.4 x 10 4 s-1M-1 when this overpotential was large. Optimum mediator potential for a cell operating with a non-limiting platinum anode and having no mass transport limitation from bulk solution was found to be 0.66 V (SHE). Redox polymers were synthesized under different concentrations, producing osmium variation. An increase from 6.6% to 7.2% osmium increased current response from 1.2 to 2.1 mA/cm2 for a planar film in 40°C oxygen-saturated pH 4 buffer, rotating at 900 rpm. These results translated to high surface area electrodes, nearly doubling current density to 13 mA/cm2, the highest to date for such an electrode. The typical fungal laccase from Trametes versicolor was replaced by a bacterially-expressed small laccase from Streptomyces coelicolor, resulting in biocatalytic films that reduced oxygen at increased pH, with full functionality at pH 7, producing 1.5 mA/cm 2 in planar configuration. Current response was biphasic with pH, matching the activity profile of the free enzyme in solution. The mediated enzyme electrode system was modeled with respect to apparent electron diffusion, mediator concentration, and transport of oxygen from bulk solution, all of which are to some extent controlled by design. Each factor was found to limit performance in certain circumstances. In systems relying on stagnant solution, oxygen transport was found to dominate. However, if mass transport was efficient, differences in mediator design greatly affected performance.

Controlling the growth of palladium aerogels with high-performance toward bioelectrocatalytic oxidation of glucose.

PubMed

Wen, Dan; Herrmann, Anne-Kristin; Borchardt, Lars; Simon, Frank; Liu, Wei; Kaskel, Stefan; Eychmüller, Alexander

2014-02-19

We report the controllable synthesis of Pd aerogels with high surface area and porosity by destabilizing colloidal solutions of Pd nanoparticles with variable concentrations of calcium ions. Enzyme electrodes based on Pd aerogels co-immobilized with glucose oxidase show high activity toward glucose oxidation and are promising materials for applications in bioelectronics.

Amperometric Glucose Sensor Using Thermostable Co-Factor Binding Glucose Dehydrogenase

NASA Astrophysics Data System (ADS)

Nakazawa, Yukie; Yamazaki, Tomohiko; Tsugawa, Wakako; Ikebukuro, Kazunori; Sode, Koji

A thermostable mediator-type enzyme glucose sensor was constructed. The electrode was fabricated using chemically cross-linked thermostable co-factor binding glucose dehydrogenase (GDH) from thermophilic bacteria in carbon paste matrix. The electrode responded directly proportional to D-glucose concentration from 0.01 mM to 3 mM in stirred buffer containing 1 mM 1-methoxyphenazinemethosulfate as a mediator with the steady-state mode. The storage stability was examined by incubating the enzyme electrode at 50oC during the measurement. The cross-linked GDH immobilized electrode showed good storage stability. Ninety percent of its initial response was retained after incubation in buffer solution for 9 days at 50oC. The flow injection analysis (FIA) glucose sensing system was also constructed by immobilizing the cross-linked GDH and ferrocene as a mediator in the carbon paste matrix. The FIA system was able to measure 600 samples for 100 h.

Development of an amperometric-based glucose biosensor to measure the glucose content of fruit.

PubMed

Ang, Lee Fung; Por, Lip Yee; Yam, Mun Fei

2015-01-01

An amperometric enzyme-electrode was introduced where glucose oxidase (GOD) was immobilized on chitosan membrane via crosslinking, and then fastened on a platinum working electrode. The immobilized enzyme showed relatively high retention activity. The activity of the immobilized enzyme was influenced by its loading, being suppressed when more than 0.6 mg enzyme was used in the immobilization. The biosensor showing the highest response to glucose utilized 0.21 ml/cm2 thick chitosan membrane. The optimum experimental conditions for the biosensors in analysing glucose dissolved in 0.1 M phosphate buffer (pH 6.0) were found to be 35°C and 0.6 V applied potential. The introduced biosensor reached a steady-state current at 60 s. The apparent Michaelis-Menten constant ([Formula: see text]) of the biosensor was 14.2350 mM, and its detection limit was 0.05 mM at s/n > 3, determined experimentally. The RSD of repeatability and reproducibility of the biosensor were 2.30% and 3.70%, respectively. The biosensor was showed good stability; it retained ~36% of initial activity after two months of investigation. The performance of the biosensors was evaluated by determining the glucose content in fruit homogenates. Their accuracy was compared to that of a commercial glucose assay kit. There was no significance different between two methods, indicating the introduced biosensor is reliable.

Development of an Amperometric-Based Glucose Biosensor to Measure the Glucose Content of Fruit

PubMed Central

Ang, Lee Fung; Por, Lip Yee; Yam, Mun Fei

2015-01-01

An amperometric enzyme-electrode was introduced where glucose oxidase (GOD) was immobilized on chitosan membrane via crosslinking, and then fastened on a platinum working electrode. The immobilized enzyme showed relatively high retention activity. The activity of the immobilized enzyme was influenced by its loading, being suppressed when more than 0.6 mg enzyme was used in the immobilization. The biosensor showing the highest response to glucose utilized 0.21 ml/cm2 thick chitosan membrane. The optimum experimental conditions for the biosensors in analysing glucose dissolved in 0.1 M phosphate buffer (pH 6.0) were found to be 35°C and 0.6 V applied potential. The introduced biosensor reached a steady-state current at 60 s. The apparent Michaelis-Menten constant (KMapp) of the biosensor was 14.2350 mM, and its detection limit was 0.05 mM at s/n > 3, determined experimentally. The RSD of repeatability and reproducibility of the biosensor were 2.30% and 3.70%, respectively. The biosensor was showed good stability; it retained ~36% of initial activity after two months of investigation. The performance of the biosensors was evaluated by determining the glucose content in fruit homogenates. Their accuracy was compared to that of a commercial glucose assay kit. There was no significance different between two methods, indicating the introduced biosensor is reliable. PMID:25789757

Hydrogen peroxide produced by glucose oxidase affects the performance of laccase cathodes in glucose/oxygen fuel cells: FAD-dependent glucose dehydrogenase as a replacement.

PubMed

Milton, Ross D; Giroud, Fabien; Thumser, Alfred E; Minteer, Shelley D; Slade, Robert C T

2013-11-28

Hydrogen peroxide production by glucose oxidase (GOx) and its negative effect on laccase performance have been studied. Simultaneously, FAD-dependent glucose dehydrogenase (FAD-GDH), an O2-insensitive enzyme, has been evaluated as a substitute. Experiments focused on determining the effect of the side reaction of GOx between its natural electron acceptor O2 (consumed) and hydrogen peroxide (produced) in the electrolyte. Firstly, oxygen consumption was investigated by both GOx and FAD-GDH in the presence of substrate. Relatively high electrocatalytic currents were obtained with both enzymes. O2 consumption was observed with immobilized GOx only, whilst O2 concentration remained stable for the FAD-GDH. Dissolved oxygen depletion effects on laccase electrode performances were investigated with both an oxidizing and a reducing electrode immersed in a single compartment. In the presence of glucose, dramatic decreases in cathodic currents were recorded when laccase electrodes were combined with a GOx-based electrode only. Furthermore, it appeared that the major loss of performance of the cathode was due to the increase of H2O2 concentration in the bulk solution induced laccase inhibition. 24 h stability experiments suggest that the use of O2-insensitive FAD-GDH as to obviate in situ peroxide production by GOx is effective. Open-circuit potentials of 0.66 ± 0.03 V and power densities of 122.2 ± 5.8 μW cm(-2) were observed for FAD-GDH/laccase biofuel cells.

Various applications of immobilized glucose oxidase and polyphenol oxidase in a conducting polymer matrix.

PubMed

Cil, M; Böyükbayram, A E; Kiralp, S; Toppare, L; Yağci, Y

2007-06-01

In this study, glucose oxidase and polyphenol oxidase were immobilized in conducting polymer matrices; polypyrrole and poly(N-(4-(3-thienyl methylene)-oxycarbonyl phenyl) maleimide-co-pyrrole) via electrochemical method. Fourier transform infrared and scanning electron microscope were employed to characterize the copolymer of (N-(4-(3-thienyl methylene)-oxycarbonyl phenyl) maleimide) with pyrrole. Kinetic parameters, maximum reaction rate and Michealis-Menten constant, were determined. Effects of temperature and pH were examined for immobilized enzymes. Also, storage and operational stabilities of enzyme electrodes were investigated. Glucose and polyphenol oxidase enzyme electrodes were used for determination of the glucose amount in orange juices and human serum and phenolic amount in red wines, respectively.

Novel amperometric glucose biosensor based on MXene nanocomposite.

PubMed

Rakhi, R B; Nayak, Pranati; Xia, Chuan; Alshareef, Husam N

2016-11-10

A biosensor platform based on Au/MXene nanocomposite for sensitive enzymatic glucose detection is reported. The biosensor leverages the unique electrocatalytic properties and synergistic effects between Au nanoparticles and MXene sheets. An amperometric glucose biosensor is fabricated by the immobilization of glucose oxidase (GOx) enzyme on Nafion solubilized Au/ MXene nanocomposite over glassy carbon electrode (GCE). The biomediated Au nanoparticles play a significant role in facilitating the electron exchange between the electroactive center of GOx and the electrode. The GOx/Au/MXene/Nafion/GCE biosensor electrode displayed a linear amperometric response in the glucose concentration range from 0.1 to 18 mM with a relatively high sensitivity of 4.2 μAmM -1 cm -2 and a detection limit of 5.9 μM (S/N = 3). Furthermore, the biosensor exhibited excellent stability, reproducibility and repeatability. Therefore, the Au/MXene nanocomposite reported in this work is a potential candidate as an electrochemical transducer in electrochemical biosensors.

Novel amperometric glucose biosensor based on MXene nanocomposite

PubMed Central

Rakhi, R. B.; Nayuk, Pranati; Xia, Chuan; Alshareef, Husam N.

2016-01-01

A biosensor platform based on Au/MXene nanocomposite for sensitive enzymatic glucose detection is reported. The biosensor leverages the unique electrocatalytic properties and synergistic effects between Au nanoparticles and MXene sheets. An amperometric glucose biosensor is fabricated by the immobilization of glucose oxidase (GOx) enzyme on Nafion solubilized Au/ MXene nanocomposite over glassy carbon electrode (GCE). The biomediated Au nanoparticles play a significant role in facilitating the electron exchange between the electroactive center of GOx and the electrode. The GOx/Au/MXene/Nafion/GCE biosensor electrode displayed a linear amperometric response in the glucose concentration range from 0.1 to 18 mM with a relatively high sensitivity of 4.2 μAmM−1 cm−2 and a detection limit of 5.9 μM (S/N = 3). Furthermore, the biosensor exhibited excellent stability, reproducibility and repeatability. Therefore, the Au/MXene nanocomposite reported in this work is a potential candidate as an electrochemical transducer in electrochemical biosensors. PMID:27830757

Laccase electrodes based on the combination of single-walled carbon nanotubes and redox layered double hydroxides: Towards the development of biocathode for biofuel cells

NASA Astrophysics Data System (ADS)

Ding, Shou-Nian; Holzinger, Michael; Mousty, Christine; Cosnier, Serge

Single-walled carbon nanotubes (SWCNT) were combined with layered double hydroxides (LDH) intercalated with 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt [ZnCr-ABTS] to entrap and electrically connect laccase enzyme. The resulting laccase electrodes exhibited an electro-enzymatic activity for O 2 reduction. To improve this electrocatalytic activity, varying SWCNT quantities and loading methods were tested to optimize the configuration of the laccase electrodes. Furthermore, the resulting bioelectrode was successfully used as a biocathode for the elaboration of a membrane-less glucose/air biofuel cell. In 0.1 M phosphate buffer (PBS) of pH 6.0, containing glucose (5 mM) under ambient conditions, the assembled biofuel cell yielded a maximum power density of 18 μW cm -2 at a cell voltage of 0.3 V whereas this power decreased to 8.3 μW cm -2 for a biofuel cell based on the identical biocathode setup without SWCNT.

Gold-Coated M13 Bacteriophage as a Template for Glucose Oxidase Biofuel Cells with Direct Electron Transfer.

PubMed

Blaik, Rita A; Lan, Esther; Huang, Yu; Dunn, Bruce

2016-01-26

Glucose oxidase-based biofuel cells are a promising source of alternative energy for small device applications, but still face the challenge of achieving robust electrical contact between the redox enzymes and the current collector. This paper reports on the design of an electrode consisting of glucose oxidase covalently attached to gold nanoparticles that are assembled onto a genetically engineered M13 bacteriophage using EDC-NHS chemistry. The engineered phage is modified at the pIII protein to attach onto a gold substrate and serves as a high-surface-area template. The resulting "nanomesh" architecture exhibits direct electron transfer (DET) and achieves a higher peak current per unit area of 1.2 mA/cm(2) compared to most other DET attachment schemes. The final enzyme surface coverage on the electrode was calculated to be approximately 4.74 × 10(-8) mol/cm(2), which is a significant improvement over most current glucose oxidase (GOx) DET attachment methods.

Nano-yarn carbon nanotube fiber based enzymatic glucose biosensor

NASA Astrophysics Data System (ADS)

Zhu, Zhigang; Song, Wenhui; Burugapalli, Krishna; Moussy, Francis; Li, Ya-Li; Zhong, Xiao-Hua

2010-04-01

A novel brush-like electrode based on carbon nanotube (CNT) nano-yarn fiber has been designed for electrochemical biosensor applications and its efficacy as an enzymatic glucose biosensor demonstrated. The CNT nano-yarn fiber was spun directly from a chemical-vapor-deposition (CVD) gas flow reaction using a mixture of ethanol and acetone as the carbon source and an iron nano-catalyst. The fiber, 28 µm in diameter, was made of bundles of double walled CNTs (DWNTs) concentrically compacted into multiple layers forming a nano-porous network structure. Cyclic voltammetry study revealed a superior electrocatalytic activity for CNT fiber compared to the traditional Pt-Ir coil electrode. The electrode end tip of the CNT fiber was freeze-fractured to obtain a unique brush-like nano-structure resembling a scale-down electrical 'flex', where glucose oxidase (GOx) enzyme was immobilized using glutaraldehyde crosslinking in the presence of bovine serum albumin (BSA). An outer epoxy-polyurethane (EPU) layer was used as semi-permeable membrane. The sensor function was tested against a standard reference electrode. The sensitivities, linear detection range and linearity for detecting glucose for the miniature CNT fiber electrode were better than that reported for a Pt-Ir coil electrode. Thermal annealing of the CNT fiber at 250 °C for 30 min prior to fabrication of the sensor resulted in a 7.5 fold increase in glucose sensitivity. The as-spun CNT fiber based glucose biosensor was shown to be stable for up to 70 days. In addition, gold coating of the electrode connecting end of the CNT fiber resulted in extending the glucose detection limit to 25 µM. To conclude, superior efficiency of CNT fiber for glucose biosensing was demonstrated compared to a traditional Pt-Ir sensor.

Immobilization of DNA onto poly(dimethylsiloxane) surfaces and application to a microelectrochemical enzyme-amplified DNA hybridization assay.

PubMed

Liu, Daojun; Perdue, Robbyn K; Sun, Li; Crooks, Richard M

2004-07-06

This paper describes immobilization of DNA onto the interior walls of poly(dimethylsiloxane) (PDMS) microsystems and its application to an enzyme-amplified electrochemical DNA assay. DNA immobilization was carried out by silanization of the PDMS surface with 3-mercaptopropyltrimethoxysilane to yield a thiol-terminated surface. 5'-acrylamide-modified DNA reacts with the pendant thiol groups to yield DNA-modified PDMS. Surface-immobilized DNA oligos serve as capture probes for target DNA. Biotin-labeled target DNA hybridizes to the PDMS-immobilized capture DNA, and subsequent introduction of alkaline phosphatase (AP) conjugated to streptavidin results in attachment of the enzyme to hybridized DNA. Electrochemical detection of DNA hybridization benefits from enzyme amplification. Specifically, AP converts electroinactive p-aminophenyl phosphate to electroactive p-aminophenol, which is detected using an indium tin oxide interdigitated array (IDA) electrode. The IDA electrode eliminates the need for a reference electrode and provides a steady-state current that is related to the concentration of hybridized DNA. At present, the limit of detection of the DNA target is 1 nM in a volume of 20 nL, which corresponds to 20 attomoles of DNA.

Mussel-Inspired Electro-Cross-Linking of Enzymes for the Development of Biosensors.

PubMed

El-Maiss, Janwa; Cuccarese, Marco; Maerten, Clément; Lupattelli, Paolo; Chiummiento, Lucia; Funicello, Maria; Schaaf, Pierre; Jierry, Loïc; Boulmedais, Fouzia

2018-06-06

In medical diagnosis and environmental monitoring, enzymatic biosensors are widely applied because of their high sensitivity, potential selectivity, and their possibility of miniaturization/automation. Enzyme immobilization is a critical process in the development of this type of biosensors with the necessity to avoid the denaturation of the enzymes and ensuring their accessibility toward the analyte. Electrodeposition of macromolecules is increasingly considered to be the most suitable method for the design of biosensors. Being simple and attractive, it finely controls the immobilization of enzymes on electrode surfaces, usually by entrapment or adsorption, using an electrical stimulus. Performed manually, enzyme immobilization by cross-linking prevents enzyme leaching and was never done using an electrochemical stimulus. In this work, we present a mussel-inspired electro-cross-linking process using glucose oxidase (GOX) and a homobifunctionalized catechol ethylene oxide spacer as a cross-linker in the presence of ferrocene methanol (FC) acting as a mediator of the buildup. Performed in one pot, the process takes place in three steps: (i) electro-oxidation of FC, by the application of cyclic voltammetry, creating a gradient of ferrocenium (FC + ); (ii) oxidation of bis-catechol into a bis-quinone molecule by reaction with the electrogenerated FC + ; and (iii) a chemical reaction of bis-quinone with free amino moieties of GOX through Michael addition and a Schiff's base condensation reaction. Employed for the design of a second-generation glucose biosensor using ferrocene methanol (FC) as a mediator, this new enzyme immobilization process presents several advantages. The cross-linked enzymatic film (i) is obtained in a one-pot process with nonmodified GOX, (ii) is strongly linked to the metallic electrode surface thanks to catechol moieties, and (iii) presents no leakage issues. The developed GOX/bis-catechol film shows a good response to glucose with a quite wide linear range from 1.0 to 12.5 mM as well as a good sensitivity (0.66 μA/mM cm 2 ) and a high selectivity to glucose. These films would distinguish between healthy (3.8 and 6.5 mM) and hyperglycemic subjects (>7 mM). Finally, we show that this electro-cross-linking process allows the development of miniaturized biosensors through the functionalization of a single electrode out of a microelectrode array. Elegant and versatile, this electro-cross-linking process can also be used for the development of enzymatic biofuel cells.

Glucose biosensors with enzyme entrapped in polymer coating.

PubMed

Yang, S; Atanasov, P; Wilkins, E

1995-01-01

The pursuit of reliable biosensors for measuring glucose levels has been ongoing for decades. Their importance lies partly in the development of the implantable artificial pancrease, which can be used to deliver insulin to diabetics without the need to test glucose levels externally, with automatic delivery based on physiologic demand. Glucose sensors can also be used in short-term monitoring of glucose levels in hospitals and clinical laboratories. Three types of glucose biosensors were studied. All were based on a two-electrode system: an insulated platinum wire as a hydrogen peroxide electrode, and a silver wire twisted around the platinum wire as both a reference and a counter electrode. Each was coated with the enzyme glucose oxidase entrapped in a polymer matrix of cellulose acetate (CA) or poly 2-hydroxyethyl methacrylate (HEMA), then dip-coated by an additional polymer coating of polyvinylchloride (PVC), polyurethane (PU), or HEMA. The experiments were designed mainly to study the effectiveness of polymer coatings as diffusion-limiting membranes. The effect of each coating on the linear response to glucose concentration was examined. It was shown that additional (multiple) coatings can increase the linearity of the sensor response. The best results were obtained when the sensor was PVC-dip-coated three times. This preparation had a linear response up to 600 mg/DL glucose concentration. The sensors coated with PU and HEMA have linearity up to 280 and 240 mg/DL glucose concentrations, respectively. It was also shown that the coatings reduce interference from certain body chemicals.

An Electrochemical Gas Biosensor Based on Enzymes Immobilized on Chromatography Paper for Ethanol Vapor Detection.

PubMed

Kuretake, Tatsumi; Kawahara, Shogo; Motooka, Masanobu; Uno, Shigeyasu

2017-02-01

This paper presents a novel method of fabricating an enzymatic biosensor for breath analysis using chromatography paper as enzyme supporting layer and a liquid phase layer on top of screen printed carbon electrodes. We evaluated the performance with ethanol vapor being one of the breathing ingredients. The experimental results show that our sensor is able to measure the concentration of ethanol vapor within the range of 50 to 500 ppm. These results suggest the ability of detecting breath ethanol, and it can possibly be applied as a generic vapor biosensor to a wide range of diseases.

Effect of Nanoparticles on Modified Screen Printed Inhibition Superoxide Dismutase Electrodes for Aluminum

PubMed Central

Barquero-Quirós, Miriam; Arcos-Martínez, María Julia

2016-01-01

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme superoxide dismutase has been developed. The oxidation signal of epinephrine substrate was affected by the presence of Al(III) ions leading to a decrease in its amperometric current. The immobilization of the enzyme was performed with glutaraldehyde on screen-printed carbon electrodes modifiedwith tetrathiofulvalene (TTF) and different types ofnanoparticles. Nanoparticles of gold, platinum, rhodium and palladium were deposited on screen printed carbon electrodes by means of two electrochemical procedures. Nanoparticles were characterized trough scanning electronic microscopy, X-rays fluorescence, and atomic force microscopy. Palladium nanoparticles showed lower atomic force microscopy parameters and higher slope of aluminum calibration curves and were selected to perform sensor validation. The developed biosensor has a detection limit of 2.0 ± 0.2 μM for Al(III), with a reproducibility of 7.9% (n = 5). Recovery of standard reference material spiked to buffer solution was 103.8% with a relative standard deviation of 4.8% (n = 5). Recovery of tap water spiked with the standard reference material was 100.5 with a relative standard deviation of 3.4% (n = 3). The study of interfering ions has also been carried out. PMID:27681735

Amperometric cholesterol biosensor based on the direct electrochemistry of cholesterol oxidase and catalase on a graphene/ionic liquid-modified glassy carbon electrode.

PubMed

Gholivand, Mohammad Bagher; Khodadadian, Mehdi

2014-03-15

Cholesterol oxidase (ChOx) and catalase (CAT) were co-immobilized on a graphene/ionic liquid-modified glassy carbon electrode (GR-IL/GCE) to develop a highly sensitive amperometric cholesterol biosensor. The H2O2 generated during the enzymatic reaction of ChOx with cholesterol could be reduced electrocatalytically by immobilized CAT to obtain a sensitive amperometric response to cholesterol. The direct electron transfer between enzymes and electrode surface was investigated by cyclic voltammetry. Both enzymes showed well-defined redox peaks with quasi-reversible behaviors. An excellent sensitivity of 4.163 mA mM(-1)cm(-2), a response time less than 6s, and a linear range of 0.25-215 μM (R(2)>0.99) have been observed for cholesterol determination using the proposed biosensor. The apparent Michaelis-Menten constant (KM(app)) was calculated to be 2.32 mM. The bienzymatic cholesterol biosensor showed good reproducibility (RSDs<5%) with minimal interference from the coexisting electroactive compounds such as ascorbic acid and uric acid. The CAT/ChOx/GR-IL/GCE showed excellent analytical performance for the determination of free cholesterol in human serum samples. © 2013 Elsevier B.V. All rights reserved.

Nanomaterial-based electrochemical sensors for arsenic - A review.

PubMed

Kempahanumakkagari, Sureshkumar; Deep, Akash; Kim, Ki-Hyun; Kumar Kailasa, Suresh; Yoon, Hye-On

2017-09-15

The existence of arsenic in the environment poses severe global health threats. Considering its toxicity, the sensing of arsenic is extremely important. Due to the complexity of environmental and biological samples, many of the available detection methods for arsenic have serious limitations on selectivity and sensitivity. To improve sensitivity and selectivity and to circumvent interferences, different electrode systems have been developed based on surface modification with nanomaterials including carbonaceous nanomaterials, metallic nanoparticles (MNPs), metal nanotubes (MNTs), and even enzymes. Despite the progress made in electrochemical sensing of arsenic, some issues still need to be addressed to realize cost effective, portable, and flow-injection type sensor systems. The present review provides an in-depth evaluation of the nanoparticle-modified electrode (NME) based methods for the electrochemical sensing of arsenic. NME based sensing systems are projected to become an important option for monitoring hazardous pollutants in both environmental and biological media. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical biosensing of galactose based on carbon materials: graphene versus multi-walled carbon nanotubes.

PubMed

Dalkıran, Berna; Erden, Pınar Esra; Kılıç, Esma

2016-06-01

In this study, two enzyme electrodes based on graphene (GR), Co3O4 nanoparticles and chitosan (CS) or multi-walled carbon nanotubes (MWCNTs), Co3O4 nanoparticles, and CS, were fabricated as novel biosensing platforms for galactose determination, and their performances were compared. Galactose oxidase (GaOx) was immobilized onto the electrode surfaces by crosslinking with glutaraldehyde. Optimum working conditions of the biosensors were investigated and the analytical performance of the biosensors was compared with respect to detection limit, linearity, repeatability, and stability. The MWCNTs-based galactose biosensor provided about 1.6-fold higher sensitivity than its graphene counterpart. Moreover, the linear working range and detection limit of the MWCNTs-based galactose biosensor was superior to the graphene-modified biosensor. The successful application of the purposed biosensors for galactose biosensing in human serum samples was also investigated.

Acetylcholinesterase inhibition-based biosensor for aluminum(III) chronoamperometric determination in aqueous media.

PubMed

Barquero-Quirós, Miriam; Domínguez-Renedo, Olga; Alonso-Lomillo, Maria Asunción; Arcos-Martínez, María Julia

2014-05-07

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme acetylcholinesterase has been developed. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles. The oxidation signal of acetylthiocholine iodide enzyme substrate was affected by the presence of Al(III) ions leading to a decrease in the amperometric current. The developed system has a detection limit of 2.1 ± 0.1 μM for Al(III). The reproducibility of the method is 8.1% (n = 4). Main interferences include Mo(VI), W(VI) and Hg(II) ions. The developed method was successfully applied to the determination of Al(III) in spiked tap water . The analysis of a certified standard reference material was also carried out. Both results agree with the certified values considering the respective associated uncertainties.

Acetylcholinesterase Inhibition-Based Biosensor for Aluminum(III) Chronoamperometric Determination in Aqueous Media

PubMed Central

Barquero-Quirós, Miriam; Domínguez-Renedo, Olga; Alonso-Lomillo, Maria Asunción; Arcos-Martínez, María Julia

2014-01-01

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme acetylcholinesterase has been developed. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles. The oxidation signal of acetylthiocholine iodide enzyme substrate was affected by the presence of Al(III) ions leading to a decrease in the amperometric current. The developed system has a detection limit of 2.1 ± 0.1 μM for Al(III). The reproducibility of the method is 8.1% (n = 4). Main interferences include Mo(VI), W(VI) and Hg(II) ions. The developed method was successfully applied to the determination of Al(III) in spiked tap water. The analysis of a certified standard reference material was also carried out. Both results agree with the certified values considering the respective associated uncertainties. PMID:24811076

An amperometric hydrogen peroxide biosensor based on Co3O4 nanoparticles and multiwalled carbon nanotube modified glassy carbon electrode

NASA Astrophysics Data System (ADS)

Kaçar, Ceren; Dalkiran, Berna; Erden, Pınar Esra; Kiliç, Esma

2014-08-01

In this work a new type of hydrogen peroxide biosensor was fabricated based on the immobilization of horseradish peroxidase (HRP) by cross-linking on a glassy carbon electrode (GCE) modified with Co3O4 nanoparticles, multiwall carbon nanotubes (MWCNTs) and gelatin. The introduction of MWCNTs and Co3O4 nanoparticles not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer rate, resulting in a high sensitivity of the biosensor. The fabrication process of the sensing surface was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric detection of hydrogen peroxide was investigated by holding the modified electrode at -0.30 V (vs. Ag/AgCl). The biosensor showed optimum response within 5 s at pH 7.0. The optimized biosensor showed linear response range of 7.4 × 10-7-1.9 × 10-5 M with a detection limit of 7.4 × 10-7. The applicability of the purposed biosensor was tested by detecting hydrogen peroxide in disinfector samples. The average recovery was calculated as 100.78 ± 0.89.

Bi-enzyme L-arginine-selective amperometric biosensor based on ammonium-sensing polyaniline-modified electrode.

PubMed

Stasyuk, Nataliya; Smutok, Oleh; Gayda, Galina; Vus, Bohdan; Koval'chuk, Yevgen; Gonchar, Mykhailo

2012-01-01

A novel L-arginine-selective amperometric bi-enzyme biosensor based on recombinant human arginase I isolated from the gene-engineered strain of methylotrophic yeast Hansenula polymorpha and commercial urease is described. The biosensing layer was placed onto a polyaniline-Nafion composite platinum electrode and covered with a calcium alginate gel. The developed sensor revealed a good selectivity to L-arginine. The sensitivity of the biosensor was 110 ± 1.3 nA/(mM mm(2)) with the apparent Michaelis-Menten constant (K(M)(app)) derived from an L-arginine (L-Arg) calibration curve of 1.27 ± 0.29 mM. A linear concentration range was observed from 0.07 to 0.6mM, a limit of detection being 0.038 mM and a response time - 10s. The developed biosensor demonstrated good storage stability. A laboratory prototype of the proposed amperometric biosensor was applied to the samples of three commercial pharmaceuticals ("Tivortin", "Cytrarginine", "Aminoplazmal 10% E") for L-Arg testing. The obtained L-Arg-content values correlated well with those declared by producers. Copyright © 2012 Elsevier B.V. All rights reserved.

Biosensing of glucose in flow injection analysis system based on glucose oxidase-quantum dot modified pencil graphite electrode.

PubMed

Sağlam, Özlem; Kızılkaya, Bayram; Uysal, Hüseyin; Dilgin, Yusuf

2016-01-15

A novel amperometric glucose biosensor was proposed in flow injection analysis (FIA) system using glucose oxidase (GOD) and Quantum dot (ZnS-CdS) modified Pencil Graphite Electrode (PGE). After ZnS-CdS film was electrochemically deposited onto PGE surface, GOD was immobilized on the surface of ZnS-CdS/PGE through crosslinking with chitosan (CT). A pair of well-defined reversible redox peak of GOD was observed at GOD/CT/ZnS-CdS/PGE based on enzyme electrode by direct electron transfer between the protein and electrode. Further, obtained GOD/CT/ZnS-CdS/PGE offers a disposable, low cost, selective and sensitive electrochemical biosensing of glucose in FIA system based on the decrease of the electrocatalytic response of the reduced form of GOD to dissolved oxygen. Under optimum conditions (flow rate, 1.3mL min(-1); transmission tubing length, 10cm; injection volume, 100μL; and constant applied potential, -500mV vs. Ag/AgCl), the proposed method displayed a linear response to glucose in the range of 0.01-1.0mM with detection limit of 3.0µM. The results obtained from this study would provide the basis for further development of the biosensing using PGE based FIA systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Future of biosensors: a personal view.

PubMed

Scheller, Frieder W; Yarman, Aysu; Bachmann, Till; Hirsch, Thomas; Kubick, Stefan; Renneberg, Reinhard; Schumacher, Soeren; Wollenberger, Ulla; Teller, Carsten; Bier, Frank F

2014-01-01

Biosensors representing the technological counterpart of living senses have found routine application in amperometric enzyme electrodes for decentralized blood glucose measurement, interaction analysis by surface plasmon resonance in drug development, and to some extent DNA chips for expression analysis and enzyme polymorphisms. These technologies have already reached a highly advanced level and need minor improvement at most. The dream of the "100-dollar" personal genome may come true in the next few years provided that the technological hurdles of nanopore technology or of polymerase-based single molecule sequencing can be overcome. Tailor-made recognition elements for biosensors including membrane-bound enzymes and receptors will be prepared by cell-free protein synthesis. As alternatives for biological recognition elements, molecularly imprinted polymers (MIPs) have been created. They have the potential to substitute antibodies in biosensors and biochips for the measurement of low-molecular-weight substances, proteins, viruses, and living cells. They are more stable than proteins and can be produced in large amounts by chemical synthesis. Integration of nanomaterials, especially of graphene, could lead to new miniaturized biosensors with high sensitivity and ultrafast response. In the future individual therapy will include genetic profiling of isoenzymes and polymorphic forms of drug-metabolizing enzymes especially of the cytochrome P450 family. For defining the pharmacokinetics including the clearance of a given genotype enzyme electrodes will be a useful tool. For decentralized online patient control or the integration into everyday "consumables" such as drinking water, foods, hygienic articles, clothing, or for control of air conditioners in buildings and cars and swimming pools, a new generation of "autonomous" biosensors will emerge.

Electrochemistry of metalloproteins: protein film electrochemistry for the study of E. coli [NiFe]-hydrogenase-1.

PubMed

Evans, Rhiannon M; Armstrong, Fraser A

2014-01-01

Protein film electrochemistry is a technique which allows the direct control of redox-active enzymes, providing particularly detailed information on their catalytic properties. The enzyme is deposited onto a working electrode tip, and through control of the applied potential the enzyme activity is monitored as electrical current, allowing for direct study of inherent activity as electrons are transferred to and from the enzyme redox center(s). No mediators are used. Because the only enzyme present in the experiment is bound at the electrode surface, gaseous and liquid phase inhibitors can be introduced and removed whilst the enzyme remains in situ. Potential control means that kinetics and thermodynamics are explored simultaneously; the kinetics of a reaction can be studied as a function of potential. Steady-state catalytic rates are observed directly as current (for a given potential) and non-steady-state rates (such as interconversions between different forms of the enzyme) are observed from the change in current with time. The more active the enzyme, the higher the current and the better the signal-to-noise. In this chapter we outline the practical aspects of PFE for studying electroactive enzymes, using the Escherichia coli [NiFe]-hydrogenase 1 (Hyd-1) as an example.

Investigating the thermostability of succinate: quinone oxidoreductase enzymes by direct electrochemistry at SWNTs-modified electrodes and FTIR spectroscopy

PubMed Central

Melin, Frederic; Noor, Mohamed R.; Pardieu, Elodie; Boulmedais, Fouzia; Banhart, Florian; Cecchini, Gary; Soulimane, Tewfik

2015-01-01

Succinate Quinone reductases (SQRs) are the enzymes which couple the oxidation of succinate and the reduction of quinones in the respiratory chain of prokaryotes and eukaryotes. We compare herein the temperature-dependent activity and structural stability of two SQRs, the first one from the mesophilic bacterium E. coli and the second one from the thermophilic bacterium T. thermophilus by a combined electrochemical and infrared spectroscopy approach. Direct electron transfer was achieved with the full membrane protein complexes at SWNTs-modified electrodes. The possible structural factors which contribute to the temperature-dependent activity of the enzymes and to the thermostability of the T. thermophiles SQR in particular, are discussed. PMID:25139263

On-Chip Evaluation of DNA Methylation with Electrochemical Combined Bisulfite Restriction Analysis Utilizing a Carbon Film Containing a Nanocrystalline Structure.

PubMed

Kurita, Ryoji; Yanagisawa, Hiroyuki; Kamata, Tomoyuki; Kato, Dai; Niwa, Osamu

2017-06-06

This paper reports an on-chip electrochemical assessment of the DNA methylation status in genomic DNA on a conductive nanocarbon film electrode realized with combined bisulfite restriction analysis (COBRA). The film electrode consists of sp 2 and sp 3 hybrid bonds and is fabricated with an unbalanced magnetron (UBM) sputtering method. First, we studied the effect of the sp 2 /sp 3 ratio of the UBM nanocarbon film electrode with p-aminophenol, which is a major electro-active product of the labeling enzyme from p-aminophenol phosphate. The signal current for p-aminophenol increases as the sp 2 content in the UBM nanocarbon film electrode increases because of the π-π interaction between aromatic p-aminophenol and the graphene-like sp 2 structure. Furthermore, the capacitative current at the UBM nanocarbon film electrode was successfully reduced by about 1 order of magnitude thanks to the angstrom-level surface flatness. Therefore, a high signal-to-noise ratio was achieved compared with that of conventional electrodes. Then, after performing an ELISA-like hybridization assay with a restriction enzyme, we undertook an electrochemical evaluation of the cytosine methylation status in DNA by measuring the oxidation current derived from p-aminophenol. When the target cytosine in the analyte sequence is methylated (unmethylated), the restriction enzyme of HpyCH4IV is able (unable) to cleave the sequence, that is, the detection probe cannot (can) hybridize. We succeeded in estimating the methylation ratio at a site-specific CpG site from the peak current of a cyclic voltammogram obtained from a PCR product solution ranging from 0.01 to 1 nM.

Construction and Characterization of a Chitosan-Immobilized-Enzyme and β-Cyclodextrin-Included-Ferrocene-Based Electrochemical Biosensor for H2O2 Detection

PubMed Central

Dong, Wenbo; Wang, Kaiyin; Chen, Yu; Li, Weiping; Ye, Yanchun; Jin, Shaohua

2017-01-01

An electrochemical detection biosensor was prepared with the chitosan-immobilized-enzyme (CTS-CAT) and β-cyclodextrin-included-ferrocene (β-CD-FE) complex for the determination of H2O2. Ferrocene (FE) was included in β-cyclodextrin (β-CD) to increase its stability. The structure of the β-CD-FE was characterized. The inclusion amount, inclusion rate, and electrochemical properties of inclusion complexes were determined to optimize the reaction conditions for the inclusion. CTS-CAT was prepared by a step-by-step immobilization method, which overcame the disadvantages of the conventional preparation methods. The immobilization conditions were optimized to obtain the desired enzyme activity. CTS-CAT/β-CD-FE composite electrodes were prepared by compositing the CTS-CAT with the β-CD-FE complex on a glassy carbon electrode and used for the electrochemical detection of H2O2. It was found that the CTS-CAT could produce a strong reduction peak current in response to H2O2 and the β-CD-FE could amplify the current signal. The peak current exhibited a linear relationship with the H2O2 concentration in the range of 1.0 × 10−7–6.0 × 10−3 mol/L. Our work provided a novel method for the construction of electrochemical biosensors with a fast response, good stability, high sensitivity, and a wide linear response range based on the composite of chitosan and cyclodextrin. PMID:28773229

Multi-input and -output logic circuits based on bioelectrocatalysis with horseradish peroxidase and glucose oxidase immobilized in multi-responsive copolymer films on electrodes.

PubMed

Yu, Xue; Lian, Wenjing; Zhang, Jiannan; Liu, Hongyun

2016-06-15

Herein, poly(N-isopropylacrylamide-co-N,N'-dimethylaminoethylmethacrylate) copolymer films were polymerized on electrode surface with a simple one-step method, and the enzyme horseradish peroxidase (HRP) was embedded in the films simultaneously, which were designated as P(NiPAAm-co-DMEM)-HRP. The films exhibited a reversible structure change with the external stimuli, such as pH, CO2, temperature and SO4(2-), causing the cyclic voltammetric (CV) response of electroactive K3Fe(CN)6 at the film electrodes to display the corresponding multi-stimuli sensitive ON-OFF behavior. Based on the switchable CV property of the system and the electrochemical reduction of H2O2 catalyzed by HRP in the films and mediated by Fe(CN)6(3-) in solution, a 5-input/3-output logic gate was established. To further increase the complexity of the logic system, another enzyme glucose oxidase (GOD) was added into the films, designated as P(NiPAAm-co-DMEM)-HRP-GOD. In the presence of oxygen, the oxidation of glucose in the solution was catalyzed by GOD in the films, and the produced H2O2 in situ was recognized and electrocatalytically reduced by HRP and mediated by Fe(CN)6(3-). Based on the bienzyme films, a cascaded or concatenated 4-input/3-output logic gate system was proposed. The present work combined the multi-responsive interface with bioelectrocatalysis to construct cascaded logic circuits, which might open a new avenue to develop biocomputing elements with more sophisticated functions and design novel glucose biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of enzyme-based coatings on intact multi-walled carbon nanotubes as highly effective electrodes in biofuel cells

NASA Astrophysics Data System (ADS)

Kim, Byoung Chan; Lee, Inseon; Kwon, Seok-Joon; Wee, Youngho; Kwon, Ki Young; Jeon, Chulmin; An, Hyo Jin; Jung, Hee-Tae; Ha, Su; Dordick, Jonathan S.; Kim, Jungbae

2017-01-01

CNTs need to be dispersed in aqueous solution for their successful use, and most methods to disperse CNTs rely on tedious and time-consuming acid-based oxidation. Here, we report the simple dispersion of intact multi-walled carbon nanotubes (CNTs) by adding them directly into an aqueous solution of glucose oxidase (GOx), resulting in simultaneous CNT dispersion and facile enzyme immobilization through sequential enzyme adsorption, precipitation, and crosslinking (EAPC). The EAPC achieved high enzyme loading and stability because of crosslinked enzyme coatings on intact CNTs, while obviating the chemical pretreatment that can seriously damage the electron conductivity of CNTs. EAPC-driven GOx activity was 4.5- and 11-times higher than those of covalently-attached GOx (CA) on acid-treated CNTs and simply-adsorbed GOx (ADS) on intact CNTs, respectively. EAPC showed no decrease of GOx activity for 270 days. EAPC was employed to prepare the enzyme anodes for biofuel cells, and the EAPC anode produced 7.5-times higher power output than the CA anode. Even with a higher amount of bound non-conductive enzymes, the EAPC anode showed 1.7-fold higher electron transfer rate than the CA anode. The EAPC on intact CNTs can improve enzyme loading and stability with key routes of improved electron transfer in various biosensing and bioelectronics devices.

Assembly of photo-bioelectrochemical cells using photosystem I-functionalized electrodes

NASA Astrophysics Data System (ADS)

Efrati, Ariel; Lu, Chun-Hua; Michaeli, Dorit; Nechushtai, Rachel; Alsaoub, Sabine; Schuhmann, Wolfgang; Willner, Itamar

2016-02-01

The design of photo-bioelectrochemical cells based on native photosynthetic reaction centres is attracting substantial recent interest as a means for the conversion of solar light energy into electrical power. In the natural photosynthetic apparatus, the photosynthetic reaction centres are coupled to biocatalytic transformations leading to CO2 fixation and O2 evolution. Although significant progress in the integration of native photosystems with electrodes for light-to-electrical energy conversion has been achieved, the conjugation of the photosystems to enzymes to yield photo-bioelectrocatalytic solar cells remains a challenge. Here we demonstrate the assembly of integrated photosystem I/glucose oxidase or glucose dehydrogenase photo-bioelectrochemical electrodes. We highlight the photonic wiring of the biocatalysts by means of photosystem I using glucose as fuel. Our results provide a general approach to assemble photo-bioelectrochemical solar cells with wide implications for solar energy conversion, bioelectrocatalysis and sensing.

Enhancing Activity and Stability of Uricase from Lactobacillus plantarum by Zeolite immobilization

NASA Astrophysics Data System (ADS)

Iswantini, D.; Nurhidayat, N.; Sarah

2017-03-01

Lactobacillus plantarum has been known be able to produce uricase for uric acid biosensor. Durability and stability of L. plantarum in generating uricase enzyme was low. Hence, we tried to enhance its durability and stability by immobilizing it onto activated 250 mg zeolite at room temperature using 100 μL L.plantarum suspension and 2.87 mM uric acid, while Michaelis-Menten constant (KM) and Vmax were obtained at 6.7431 mM and 0.9171 µA consecutively, and the linearity range was 0.1-3.3 mM (R2 = 0.9667). Limit of detection (LOD) and limit of quantification (LOQ) value of the measurement were 0.4827 mM and 1.6092 mM respectively. Biosensor stability treatment was carried out in two different treatments, using the same electrode and using disposable electrode. The disposable electrode stability showed better result based on repeated measurements, but stability was still need improvement.

Catechol-chitosan redox capacitor for added amplification in electrochemical immunoanalysis.

PubMed

Yan, Kun; Liu, Yi; Guan, Yongguang; Bhokisham, Narendranath; Tsao, Chen-Yu; Kim, Eunkyoung; Shi, Xiao-Wen; Wang, Qin; Bentley, William E; Payne, Gregory F

2018-05-22

Antibodies are common recognition elements for molecular detection but often the signals generated by their stoichiometric binding must be amplified to enhance sensitivity. Here, we report that an electrode coated with a catechol-chitosan redox capacitor can amplify the electrochemical signal generated from an alkaline phosphatase (AP) linked immunoassay. Specifically, the AP product p-aminophenol (PAP) undergoes redox-cycling in the redox capacitor to generate amplified oxidation currents. We estimate an 8-fold amplification associated with this redox-cycling in the capacitor (compared to detection by a bare electrode). Importantly, this capacitor-based amplification is generic and can be coupled to existing amplification approaches based on enzyme-linked catalysis or magnetic nanoparticle-based collection/concentration. Thus, the capacitor should enhance sensitivities in conventional immunoassays and also provide chemical to electrical signal transduction for emerging applications in molecular communication. Copyright © 2018 Elsevier B.V. All rights reserved.

A selective and sensitive D-xylose electrochemical biosensor based on xylose dehydrogenase displayed on the surface of bacteria and multi-walled carbon nanotubes modified electrode.

PubMed

Li, Liang; Liang, Bo; Shi, Jianguo; Li, Feng; Mascini, Marco; Liu, Aihua

2012-03-15

A novel Nafion/bacteria-displaying xylose dehydrogenase (XDH)/multi-walled carbon nanotubes (MWNTs) composite film-modified electrode was fabricated and applied for the sensitive and selective determination of d-xylose (INS 967), where the XDH-displayed bacteria (XDH-bacteria) was prepared using a newly identified ice nucleation protein from Pseudomonas borealis DL7 as an anchoring motif. The XDH-displayed bacteria can be used directly, eliminating further enzyme-extraction and purification, thus greatly improved the stability of the enzyme. The optimal conditions for the construction of biosensor were established: homogeneous Nafion-MWNTs composite dispersion (10 μL) was cast onto the inverted glassy carbon electrode, followed by casting 10-μL of XDH-bacteria aqueous solution to stand overnight to dry, then a 5-μL of Nafion solution (0.05 wt%) is syringed to the electrode surface. The bacteria-displaying XDH could catalyze the oxidization of xylose to xylonolactone with coenzyme NAD(+) in 0.1M PBS buffer (pH7.4), where NAD(+) (nicotinamide adenine dinucleotide) is reduced to NADH (the reduced form of nicotinamide adenine dinucleotide). The resultant NADH is further electrocatalytically oxidized by MWNTs on the electrode, resulting in an obvious oxidation peak around 0.50 V (vs. Ag/AgCl). In contrast, the bacteria-XDH-only modified electrode showed oxidation peak at higher potential of 0.7 V and less sensitivity. Therefore, the electrode/MWNTs/bacteria-XDH/Nafion exhibited good analytical performance such as long-term stability, a wide dynamic range of 0.6-100 μM and a low detection limit of 0.5 μM D-xylose (S/N=3). No interference was observed in the presence of 300-fold excess of other saccharides including D-glucose, D-fructose, D-maltose, D-galactose, D-mannose, D-sucrose, and D-cellbiose as well as 60-fold excess of L-arabinose. The proposed microbial biosensor is stable, specific, sensitive, reproducible, simple, rapid and cost-effective, which holds great potential in real applications. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication and Characterization of Ultrathin-ring Electrodes for Pseudo-steady-state Amperometric Detection.

PubMed

Kitazumi, Yuki; Hamamoto, Katsumi; Noda, Tatsuo; Shirai, Osamu; Kano, Kenji

2015-01-01

The fabrication of ultrathin-ring electrodes with a diameter of 2 mm and a thickness of 100 nm is established. The ultrathin-ring electrodes provide a large density of pseudo-steady-state currents, and realize pseudo-steady-state amperometry under quiescent conditions without a Faraday cage. Under the limiting current conditions, the current response at the ultrathin-ring electrode can be well explained by the theory of the microband electrode response. Cyclic voltammograms at the ultrathin-ring electrode show sigmoidal characteristics with some hysteresis. Numerical simulation reveals that the hysteresis can be ascribed to the time-dependence of pseudo-steady-state current. The performance of amperometry with the ultrathin-ring electrode has been verified in its application to redox enzyme kinetic measurements.

Towards timely Alzheimer diagnosis: A self-powered amperometric biosensor for the neurotransmitter acetylcholine.

PubMed

Moreira, Felismina T C; Sale, M Goreti F; Di Lorenzo, Mirella

2017-01-15

Serious brain disorders, such as the Alzheimer's Disease (AD), are associated with a marked drop in the levels of important neurotransmitters, such as acetylcholine (ACh). Real time monitoring of such biomarkers can therefore play a critical role in enhancing AD therapies by allowing timely diagnosis, verifications of treatment effectiveness, and developments of new medicines. In this study, we present the first acetylcholine/oxygen hybrid enzymatic fuel cell for the self-powered on site detection of ACh in plasma, which is based on the combination of an enzymatic anode with a Pt cathode. Firstly, an effective acetylcholinesterase immobilized electrode was developed and its electrochemical performance evaluated. Highly porous gold was used as the electrode material, and the enzyme was immobilized via a one step rapid and simple procedure that does not require the use of harsh chemicals or any electrode/enzyme pre-treatments. The resulting enzymatic electrode was subsequently used as the anode of a miniature flow-through membrane-less fuel cell and showed excellent response to varying concentrations of ACh. The peak power generated by the fuel cell was 4nW at a voltage of 260mV and with a current density of 9μAcm -2 . The limit of detection of the fuel cell sensor was 10μM, with an average response time as short as 3min. These exciting results open new horizons for point-of-care Alzheimer diagnosis and provide an attractive potential alternative to established methods that require laborious and time-consuming sample treatments and expensive instruments. Copyright © 2016 Elsevier B.V. All rights reserved.

An integrated bienzyme glucose oxidase-fructose dehydrogenase-tetrathiafulvalene-3-mercaptopropionic acid-gold electrode for the simultaneous determination of glucose and fructose.

PubMed

Campuzano, Susana; Loaiza, Oscar A; Pedrero, María; de Villena, F Javier Manuel; Pingarrón, José M

2004-06-01

A bienzyme biosensor for the simultaneous determination of glucose and fructose was developed by coimmobilising glucose oxidase (GOD), fructose dehydrogenase (FDH), and the mediator, tetrathiafulvalene (TTF), by cross-linking with glutaraldehyde atop a 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM) on a gold disk electrode (AuE). The performance of this bienzyme electrode under batch and flow injection (FI) conditions, as well as an amperometric detection in high-performance liquid chromatography (HPLC), are reported. The order of enzyme immobilisation atop the MPA-SAM affected the biosensor amperometric response in terms of sensitivity, with the immobilisation order GOD, FDH, TTF being selected. Similar analytical characteristics to those obtained with single GOD or FDH SAM-based biosensors for glucose and fructose were achieved with the bienzyme electrode, indicating that no noticeable changes in the biosensor responses to the analytes occurred as a consequence of the coimmobilisation of both enzymes on the same MPA-AuE. The suitability of the bienzyme biosensor for the analysis of real samples under flow injection conditions was tested by determining glucose in two certified serum samples. The simultaneous determination of glucose and fructose in the same sample cannot be performed without a separation step because at the detection potential used (+0.10 V), both sugars show amperometric response. Consequently, HPLC with amperometric detection at the TTF-FDH-GOD-MPA-AuE was accomplished. Glucose and fructose were simultaneously determined in honey, cola softdrink, and commercial apple juice, and the results were compared with those obtained by using other reference methods.

Amine oxidase-based biosensors for spermine and spermidine determination.

PubMed

Boffi, Alberto; Favero, Gabriele; Federico, Rodolfo; Macone, Alberto; Antiochia, Riccarda; Tortolini, Cristina; Sanzó, Gabriella; Mazzei, Franco

2015-02-01

The present work describes the development and optimization of electrochemical biosensors for specific determination of the biogenic polyamine spermine (Spm) and spermidine (Spmd) whose assessment represents a novel important analytical tool in food analysis and human diagnostics. These biosensors have been prepared using novel engineered enzymes: polyamine oxidase (PAO) endowed with selectivity towards Spm and Spmd and spermine oxidase (SMO) characterized by strict specificity towards Spm. The current design entails biosensors in which the enzymes were entrapped in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ), a photocrosslinkable gel, onto an electrode surface. Screen-printed electrodes (SPEs) were used as electrochemical transducers for enzymatically produced hydrogen peroxide, operating at different potential vs Ag/AgCl according to the material of the working electrode (WE): +700 mV for graphite (GP) or -100 mV for Prussian blue (PB)-modified SPE, respectively. Biosensor performances were evaluated by means of flow injection amperometric (FIA) measurements. The modified electrodes showed good sensitivity, long-term stability and reproducibility. Under optimal conditions, the PAO biosensor showed a linear range 0.003-0.3 mM for Spm and 0.01-0.4 mM for Spmd, while with the SMO biosensor, a linear range of 0.004-0.5 mM for Spm has been obtained. The main kinetic parameters apparent Michaelis constant (K M), turnover number (K cat) and steady-state current (I max) were determined. The proposed device was then applied to the determination of biogenic amines in blood samples. The results obtained were in good agreement with those obtained with the GC-MS reference method.

Enhanced electrochemical sensitivity of enzyme precipitate coating (EPC)-based glucose oxidase biosensors with increased free CNT loadings.

PubMed

Kim, Jae Hyun; Jun, Sun-Ae; Kwon, Yongchai; Ha, Su; Sang, Byong-In; Kim, Jungbae

2015-02-01

Enzymatic electrodes were fabricated by using three different immobilizations of glucose oxidase (GOx): covalent enzyme attachment (CA), enzyme coating (EC), and enzyme precipitate coating (EPC), here referred to as CA-E, EC-E, and EPC-E, respectively. When additional carbon nanotubes (CNTs) were introduced from 0 to 75wt% for the EPC-E design, its initial biosensor sensitivity was improved from 2.40×10(-3) to 16.26×10(-3) A∙M(-1)∙cm(-2), while its electron charge transfer rate constant was increased from 0.33 to 1.47s(-1). When a fixed ratio of CNTs was added for three different electrode systems, EPC-E showed the best glucose sensitivity and long-term thermal stability. For example, when 75wt% of additional CNTs was added, the initial sensitivity of EPC-E was 16.26×10(-3) A∙M(-1)∙cm(-2), while those of EC-E and CA-E were only 6.42×10(-3) and 1.18×10(-3) A∙M(-1)∙cm(-2), respectively. Furthermore, EPC-E retained 63% of its initial sensitivity after thermal treatment at 40°C over 41days, while EC-E and CA-E showed only 12% and 1% of initial sensitivities, respectively. Consequently, the EPC approach with additional CNTs achieved both high sensitivity and long-term stability, which are required for continuous and accurate glucose monitoring. Copyright © 2014 Elsevier B.V. All rights reserved.

An improved amperometric creatinine biosensor based on nanoparticles of creatininase, creatinase and sarcosine oxidase.

PubMed

Kumar, Parveen; Jaiwal, Ranjana; Pundir, C S

2017-11-15

An improved amperometric biosensor for detection of creatinine was developed based on immobilization of nanoparticles (NPs) of creatininase (CA), creatinase (CI), and sarcosine oxidase (SOx) onto glassy carbon (GC) electrode. Transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR) were employed for characterization of enzyme nanoparticles (ENPs). The GC electrode was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) at different stages of its amendment. The biosensor showed optimum response within 2s at pH 6.0 in 0.1 M sodium phosphate buffer and 25 °C, when operated at 1.0 V against Ag/AgCl. Biosensor exhibited wider linear range from 0.01 μM to 12 μM with a limit of detection (LOD) of 0.01 μM. The analytical recoveries of added creatinine in sera were 97.97 ± 0.1% for 0.1 mM and 98.76 ± 0.2% for 0.15 mM, within and between batch coefficients of variation (CV) were 2.06% and 3.09% respectively. A good correlation (R 2  = 0.99) was observed between sera creatinine values obtained by standard enzymic colorimetric method and the present biosensor. This biosensor measured creatinine level in sera of apparently healthy subjects and persons suffering from renal and muscular dysfunction. The ENPs electrode lost 10% of its initial activity within 240 days of its regular uses, when stored at 4 °C. Copyright © 2017 Elsevier Inc. All rights reserved.

New CNT/poly(brilliant green) and CNT/poly(3,4-ethylenedioxythiophene) based electrochemical enzyme biosensors.

PubMed

Barsan, Madalina M; Pifferi, Valentina; Falciola, Luigi; Brett, Christopher M A

2016-07-13

A combination of the electroactive polymer poly(brilliant green) (PBG) or conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) with carbon nanotubes to obtain CNT/PBG and CNT/PEDOT modified carbon film electrodes (CFE) has been investigated as a new biosensor platform, incorporating the enzymes glucose oxidase (GOx) as test enzyme, alcohol oxidase (AlcOx) or alcohol dehydrogenase (AlcDH). The sensing parameters were optimized for all biosensors based on CNT/PBG/CFE, CNT/PEDOT/CFE platforms. Under optimized conditions, both GOx biosensors exhibited very similar sensitivities, while in the case of AlcOx and AlcDH biosensors, AlcOx/CNT/PBG/CFE was found to give a higher sensitivity and lower detection limit. The influence of dissolved O2 on oxidase-biosensor performance was investigated and was shown to be different for each enzyme. Comparisons were made with similar reported biosensors, showing the advantages of the new biosensors, and excellent selectivity against potential interferents was successfully demonstrated. Finally, alcohol biosensors were successfully used for the determination of ethanol in alcoholic beverages. Copyright © 2016 Elsevier B.V. All rights reserved.

Biomonitoring of Organophosphorus Agent Exposure by Reactivation of Cholinesterase Enzyme Based on Carbon Nanotube-Enhanced Flow-Injection Amperometric Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Dan; Wang, Jun; Smith, Jordan N.

2009-11-15

A portable, rapid, and sensitive assessment of sub-clinical organophosphorus (OPs) agent exposure based on reactivation of cholinesterase (ChE) from OP-inhibited ChE using rat saliva (in vitro) was developed using an electrochemical sensor coupled with a microflow-injection system. The sensor was based on a carbon nanotube (CNT)-modified screen printed carbon electrode (SPE), which was integrated into a flow cell. Due to the extent of inter-individual ChE activity variability, ChE biomonitoring often requires an initial base-line determination (non-inhibited) of enzyme activity which is then directly compared with activity after OP exposure. This manuscript described an alternative strategy where reactivation of the phosphorylatedmore » enzyme was exploited to enable measurement of both inhibited and baseline ChE activity (i.e. after reactivation) in the same sample. The use of CNT makes the electrochemical detection of the products from enzymatic reactions more feasible with extremely high sensitivity and at low potentials. Paraoxon was selected as a model OP compound for in vitro inhibition studies. Some experiment parameters, (e.g. inhibition and reactivation times), have been optimized such that, 92 - 95% ChE reactivation can be achieved over a broad range of ChE inhibition (5 - 94 %) with paraoxon. The extent of enzyme inhibition using this electrochemical sensor correlates well with conventional enzyme activity measurements.« less

Performance comparison between multienzymes loaded single and dual electrodes for the simultaneous electrochemical detection of adenosine and metabolites in cancerous cells.

PubMed

Hussain, Khalil K; Akhtar, Mahmood H; Kim, Moo-Hyun; Jung, Dong-Keun; Shim, Yoon-Bo

2018-06-30

The analytical performance of the multi enzymes loaded single electrode sensor (SES) and dual electrode sensor (DES) was compared for the detection of adenosine and metabolites. The SES was fabricated by covalent binding of tri-enzymes, adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and xanthine oxidase (XO) along with hydrazine (Hyd) onto a functionalized conducting polymer [2,2:5,2-terthiophene-3-(p-benzoic acid)] (pTTBA). The enzyme reaction electrode in DES was fabricated by covalent binding of ADA and PNP onto pTTBA coated on Au nanoparticles. The detection electrode in DES was constructed by covalent binding of XO and Hyd onto pTTBA coated on porous Au. Due to the higher amount (3.5 folds) of the immobilized enzymes and Hyd onto the DES than SES, and the lower Michaelis constant (Km) value for DES (28.7 µM) compared to SES (36.1 µM), the sensitivity was significantly enhanced for the DES (8.2 folds). The dynamic range obtained using DES was from 0.5 nM to 120.0 µM with a detection limit of 1.43 nM ± 0.02, 0.76 nM ± 0.02, and 0.48 nM ± 0.01, for adenosine (AD), inosine (IN), and hypoxanthine (Hypo) respectively. Further, the DES was coupled with an electrochemical potential modulated microchannel for the separation and simultaneous detection of AD, IN, and Hypo in an extracellular matrix of cancerous (A549) and non-cancerous (Vero) cells. The sensor probe confirms a higher basal level of extracellular AD and its metabolites in cancer cells compared to normal cells. In addition, the effect of dipyridamole on released adenosine in A549 cells was investigated. Copyright © 2018 Elsevier B.V. All rights reserved.

Partially reduced graphene oxide-gold nanorods composite based bioelectrode of improved sensing performance.

PubMed

Nirala, Narsingh R; Abraham, Shiju; Kumar, Vinod; Pandey, Shobhit A; Yadav, Umakant; Srivastava, Monika; Srivastava, S K; Singh, Vidya Nand; Kayastha, Arvind M; Srivastava, Anchal; Saxena, Preeti S

2015-11-01

The present work proposes partially reduced graphene oxide-gold nanorods supported by chitosan (CH-prGO-AuNRs) as a potential bioelectrode material for enhanced glucose sensing. Developed on ITO substrate by immobilizing glucose oxidase on CH-prGO-AuNRs composite, these CH-prGO-AuNRs/ITO bioelectrodes demonstrate high sensitivity of 3.2 µA/(mg/dL)/cm(2) and linear range of 25-200 mg/dL with an ability to detect as low as 14.5 mg/dL. Further, these CH-prGO-AuNRs/ITO based electrodes attest synergistiacally enhanced sensing properties when compared to simple graphene oxide based CH-GO/ITO electrode. This is evident from one order higher electron transfer rate constant (Ks) value in case of CH-prGO-AuNRs modified electrode (12.4×10(-2) cm/s), in contrast to CH-GO/ITO electrode (6×10(-3) cm/s). Additionally, very low Km value [15.4 mg/dL(0.85 mM)] ensures better binding affinity of enzyme to substrate which is desirable for good biosensor stability and resistance to environmental interferences. Hence, with better loading capacity, kinetics and stability, the proposed CH-prGO-AuNRs composite shows tremendous potential to detect several bio-analytes in the coming future. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation of carbon paste electrodes including poly(styrene) attached glycine-Pt(IV) for amperometric detection of glucose.

PubMed

Dönmez, Soner; Arslan, Fatma; Sarı, Nurşen; Kurnaz Yetim, Nurdan; Arslan, Halit

2014-04-15

In this study, a novel carbon paste electrode that is sensitive to glucose was prepared using the nanoparticles modified (4-Formyl-3-methoxyphenoxymethyl) with polystyren (FMPS) with L-Glycine-Pt(IV) complexes. Polymeric nanoparticles having Pt(IV) ion were prepared from (4-Formyl-3-methoxyphenoxymethyl) polystyren, glycine and PtCl4 by template method. Glucose oxidase enzyme was immobilized to a modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Determination of glucose was carried out by oxidation of enzymatically produced H2O2 at 0.5 V vs. Ag/AgCl. Effects of pH and temperature were investigated, and optimum parameters were found to be 8.0 and 55°C, respectively. Linear working range of the electrode was 5.0×10(-6)-1.0×10(-3) M, R(2)=0.997. Storage stability and operational stability of the enzyme electrode were also studied. Glucose biosensor gave perfect reproducible results after 10 measurements with 2.3% relative standard deviation. Also, it had good storage stability (gave 53.57% of the initial amperometric response at the end of 33th day). © 2013 Published by Elsevier B.V.

Ferrocene-Modified Linear Poly(ethylenimine) for Enzymatic Immobilization and Electron Mediation.

PubMed

Hickey, David P

2017-01-01

Enzymatic glucose biosensors and biofuel cells make use of the electrochemical transduction between an oxidoreductase enzyme, such as glucose oxidase (GOx), and an electrode to either quantify the amount of glucose in a solution or generate electrical energy. However, many enzymes including GOx are not able to electrochemically interact with an electrode surface directly, but require an external electrochemical relay to shuttle electrons to the electrode. Ferrocene-modified linear poly(ethylenimine) (Fc-LPEI) redox polymers have been designed to simultaneously immobilize glucose oxidase (GOx) at an electrode and mediate electron transfer from their flavin adenine dinucleotide (FAD) active site to the electrode surface. Cross-linked films of Fc-LPEI create hydrogel networks that allow for rapid transport of glucose, while the covalently bound ferrocene moieties are able to facilitate rapid electron transfer due to the ability of ferrocene to exchange electrons between adjacent ferrocene residues. For these reasons, Fc-LPEI films have been widely used in the development of high current density bioanode materials. This chapter describes the synthesis of a commonly used dimethylferrocene-modified linear poly(ethylenimine), as well as the subsequent preparation and electrochemical characterization of a GOx bioanode film utilizing the synthesized polymer.

A model system for targeted drug release triggered by biomolecular signals logically processed through enzyme logic networks.

PubMed

Mailloux, Shay; Halámek, Jan; Katz, Evgeny

2014-03-07

A new Sense-and-Act system was realized by the integration of a biocomputing system, performing analytical processes, with a signal-responsive electrode. A drug-mimicking release process was triggered by biomolecular signals processed by different logic networks, including three concatenated AND logic gates or a 3-input OR logic gate. Biocatalytically produced NADH, controlled by various combinations of input signals, was used to activate the electrochemical system. A biocatalytic electrode associated with signal-processing "biocomputing" systems was electrically connected to another electrode coated with a polymer film, which was dissolved upon the formation of negative potential releasing entrapped drug-mimicking species, an enzyme-antibody conjugate, operating as a model for targeted immune-delivery and consequent "prodrug" activation. The system offers great versatility for future applications in controlled drug release and personalized medicine.

Polymer immobilized enzyme optrodes for the detection of penicillin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulp, T.J.; Camins, I.; Angel, S.M.

The preparation and performance of two enzyme-based fiber-optic sensors (optrodes) capable of detecting penicillin are described. Each sensor consists of a polymer membrane that is covalently attached to the tip of a glass optical fiber. The membrane contains the enzyme penicillinase and a pH-sensitive fluorescent dye. A signal is produced when the enzyme catalyzes the cleavage of the ..beta..-lactam ring of penicillin to produce penicilloic acid and, consequently, a pH change in the microenvironment of the membrane. The sensors differ in the way the polymer membrane is constructed and in the type of pH indicator dye used. Both optrodes exhibitmore » response times (40-60 s) significantly lower than those of the corresponding enzyme electrodes (2 min). Each gives a linear response over the concentration range of 0.00025 to 0.01 M penicillin G, when measured in a 0.005 M phosphate buffer. The data indicate that these immobilization strategies produce similar results and may be considered complementary alternatives in future enzyme optrode applications.« less

Simulation of an enzyme-based glucose sensor

NASA Astrophysics Data System (ADS)

Sha, Xianzheng; Jablecki, Michael; Gough, David A.

2001-09-01

An important biosensor application is the continuous monitoring blood or tissue fluid glucose concentration in people with diabetes. Our research focuses on the development of a glucose sensor based on potentiostatic oxygen electrodes and immobilized glucose oxidase for long- term application as an implant in tissues. As the sensor signal depends on many design variables, a trial-and-error approach to sensor optimization can be time-consuming. Here, the properties of an implantable glucose sensor are optimized by a systematic computational simulation approach.

Microchip-Based Organophosphorus Detection Using Bienzyme Bioelectrocatalysis

NASA Astrophysics Data System (ADS)

Han, Yong Duk; Jeong, Chi Yong; Lee, Jun Hee; Lee, Dae-Sik; Yoon, Hyun C.

2012-06-01

We have developed a microsystem for the detection of organophosphorus (OP) compounds using acetylcholine esterase (AchE) and choline oxidase (ChOx) bienzyme bioelectrocatalysis. Because AchE is irreversibly inhibited by OP pesticides, the change in AchE activity with OP treatment can be traced to determine OP concentration. Polymer-associated ChOx immobilization on the working electrode surface and magnetic microparticle (MP)-assisted AchE deposition methods were employed to create an AchE-ChOx bienzyme-modified biosensing system. ChOx was immobilized on the micropatterned electrodes using poly(L-lysine), glutaraldehyde, and amine-rich interfacial surface. AchE was immobilized on the MP surface via Schiff's base formation, and the enzyme-modified MPs were deposited on the working electrode using a magnet under the microfluidic channel. The bioelectrocatalytic reaction between AchE-ChOx bienzyme cascade and the ferrocenyl electron shuttle was successfully used to detect OP with the developed microchip. This provides a self-contained and relatively easy method for OP detection. It requires minimal time and a small sample size, and has potential analytic applications in pesticides and chemical warfare agents.

Exploration of two-enzyme coupled catalysis system using scanning electrochemical microscopy.

PubMed

Wu, Zeng-Qiang; Jia, Wen-Zhi; Wang, Kang; Xu, Jing-Juan; Chen, Hong-Yuan; Xia, Xing-Hua

2012-12-18

In biological metabolism, a given metabolic process usually occurs via a group of enzymes working together in sequential pathways. To explore the metabolism mechanism requires the understanding of the multienzyme coupled catalysis systems. In this paper, an approach has been proposed to study the kinetics of a two-enzyme coupled reaction using SECM combining numerical simulations. Acetylcholine esterase and choline oxidase are immobilized on cysteamine self-assembled monolayers on tip and substrate gold electrodes of SECM via electrostatic interactions, respectively. The reaction kinetics of this two-enzyme coupled system upon various separation distance precisely regulated by SECM are measured. An overall apparent Michaelis-Menten constant of this enzyme cascade is thus measured as 2.97 mM at an optimal tip-substrate gap distance of 18 μm. Then, a kinetic model of this enzyme cascade is established for evaluating the kinetic parameters of individual enzyme by using the finite element method. The simulated results demonstrate the choline oxidase catalytic reaction is the rate determining step of this enzyme cascade. The Michaelis-Menten constant of acetylcholine esterase is evaluated as 1.8 mM. This study offers a promising approach to exploring mechanism of other two-enzyme coupled reactions in biological system and would promote the development of biosensors and enzyme-based logic systems.

DETERMINATION OF PHENOLS IN ENVIRONMENTALLY RELEVANT MATRICES WITH THE USE OF LIQUID CHROMATOGRAPHY WITH AN ENZYME ELECTRODE DETECTOR

EPA Science Inventory

A simple and rapid assay using HPLC with a tyrosinase-containing carbon paste electrode (Tyr-CPE) detector is demonstrated for the detection of phenol, p-cresol, p-methoxyphenol, and p-chlorophenol in environmental matrices. These compounds were measured in contaminated aqueous...

Electrical detection of DNA hybridization: three extraction techniques based on interdigitated Al/Al2O3 capacitors.

PubMed

Moreno-Hagelsieb, L; Foultier, B; Laurent, G; Pampin, R; Remacle, J; Raskin, J-P; Flandre, D

2007-04-15

Based on interdigitated aluminum electrodes covered with Al(2)O(3) and silver precipitation via biotin-antibody coupled gold nano-labels as signal enhancement, three complementary electrical methods were used and compared to detect the hybridization of target DNA for concentrations down to the 50 pM of a PCR product from cytochrome P450 2b2 gene. Human hepatic cytochrome P450 (CYP) enzymes participate in detoxification metabolism of xenobiotics. Therefore, determination of mutational status of P450 gene in a patient could have a significant impact on the choice of a medical treatment. Our three electrical extraction procedures are performed on the same interdigitated capacitive sensor lying on a passivated silicon substrate and consist in the measurement of respectively the low-frequency inter-electrodes capacitance, the high-frequency self-resonance frequency, and the equivalent MOS capacitance between the short-circuited electrodes and the backside metallization of the silicon substrate. This study is the first of its kind as it opens the way for correlation studies and noise reduction techniques based on multiple electrical measurements of the same DNA hybridization event with a single sensor.

Fabrication of an electrochemical platform based on the self-assembly of graphene oxide-multiwall carbon nanotube nanocomposite and horseradish peroxidase: direct electrochemistry and electrocatalysis

NASA Astrophysics Data System (ADS)

Zhang, Qian; Yang, Shaojun; Zhang, Jing; Zhang, Ling; Kang, Pingli; Li, Jinghong; Xu, Jingwei; Zhou, Hua; Song, Xi-Ming

2011-12-01

A novel hybrid nanomaterial (GO-MWNTs) was explored based on the self-assembly of multiwall carbon nanotubes (MWNTs) and graphene oxide (GO). Compared with pristine MWNTs, such a nanocomposite could be well dispersed in aqueous solution and exhibit a negative charge. Driven by the electrostatic interaction, positively charged horseradish peroxidase (HRP) could then be immobilized onto GO-MWNTs at the surface of a glassy carbon (GC) electrode to form a HRP/GO-MWNT/GC electrode under mild conditions. TEM was used to characterize the morphology of the GO-MWNT nanocomposite. UV-vis and FTIR spectra suggested that HRP was immobilized onto the hybrid matrix without denaturation. Furthermore, the immobilized HRP showed enhanced direct electron transfer for the HRP-Fe(III)/Fe(II) redox center. Based on the direct electron transfer of the immobilized HRP, the HRP/GO-MWNT/GC electrode exhibited excellent electrocatalytic behavior to the reduction of H2O2 and NaNO2, respectively. Therefore, GO-MWNTs could provide a novel and efficient platform for the immobilization and biosensing of redox enzymes, and thus may find wide potential applications in the fabrication of biosensors, biomedical devices, and bioelectronics.

Cerium phosphate nanotubes: synthesis, characterization and biosensing

NASA Astrophysics Data System (ADS)

Meng, Ling; Yang, Lige; Zhou, Bo; Cai, Chenxin

2009-01-01

Cerium phosphate (CeP) nanotubes have been synthesized and confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The 1D nanomaterial has a monoclinic crystal structure with a mean width of 15-20 nm and a length up to several micrometers. The nanotubes have been employed as electrode substrates for immobilization and direct electrochemistry of heme proteins/enzymes with myoglobin (Mb) as a model. The electrochemical characteristics of the Mb-CeP/GC electrode were studied by voltammetry. After being immobilized on the nanotubes, Mb can keep its natural structure and undergo effective direct electron transfer reaction with a pair of well-defined redox peaks at -(367 ± 3) mV (pH 7.5). The apparent electron transfer rate constant is (9.1 ± 1.4) s-1. The electrode displays good features in the electrocatalytic reduction of H2O2, and thus can be used as a biosensor for detecting the substrate with a low detection limit (0.5 ± 0.05 µM), a wide linear range (0.01-2 mM), high sensitivity (14.4 ± 1.2 µA mM-1), as well as good stability and reproducibility. CeP nanotubes can become a simple and effective biosensing platform for the integration of heme proteins/enzymes and electrodes, which can provide analytical access to a large group of enzymes for a wide range of bioelectrochemical applications.

Development of electrochemical based sandwich enzyme linked immunosensor for Cryptosporidium parvum detection in drinking water.

PubMed

Thiruppathiraja, Chinnasamy; Saroja, Veerappan; Kamatchiammal, Senthilkumar; Adaikkappan, Periyakaruppan; Alagar, Muthukaruppan

2011-10-01

Cryptosporidium parvum is one of the most important biological contaminants in drinking water and generates significant risks to public health. Due to low infectious dose of C. parvum, remarkably sensitive detection methods are required for water and food industry analysis. This present study describes a simple, sensitive, enzyme amplified sandwich form of an electrochemical immunosensor using dual labeled gold nanoparticles (alkaline phosphatase and anti-oocysts monoclonal antibody) in indium tin oxide (ITO) as an electrode to detect C. parvum. The biosensor was fabricated by immobilizing the anti-oocysts McAb on a gold nanoparticle functionalized ITO electrode, followed by the corresponding capture of analytes and dual labeled gold nanoparticle probe to detect the C. parvum target. The outcome shows the sensitivity of electrochemical immune sensor enhanced by gold nanoparticles with a limit of detection of 3 oocysts/mL in a minimal processing period. Our results demonstrated the sensitivity of the new approach compared to the customary method and the immunosensors showed acceptable precision, reproducibility, stability, and could be readily applied to multi analyte determination for environmental monitoring.

Microbial biosensor for detection of methyl parathion using screen printed carbon electrode and cyclic voltammetry.

PubMed

Kumar, Jitendra; D'Souza, S F

2011-07-15

Whole cells of recombinant Escherichia coli were immobilized on the screen printed carbon electrode (SPCE) using glutaraldehyde. Recombinant E. coli was having high periplasmic expression of organophosphorus hydrolase enzyme, which hydrolyzes the methyl parathion into two products, p-nitrophenol and dimethyl thiophosphoric acid. Cells immobilized SPCE was studied under SEM. Cells immobilized SPCE was associated with cyclic voltammetry and cyclic voltammograms were recorded before and after hydrolysis of methyl parathion. Detection was calibrated based on the relationship between the changes in the current observed at +0.1 V potential, because of redox behavior of the hydrolyzed product p-nitrophenol. As concentration of methyl parathion was increased the oxidation current also increased. Only 20 μl volume of the sample was required for analysis. Detection range of biosensor was calibrated between 2 and 80 μM of methyl parathion from the linear range of calibration plot. A single immobilized SPCE was reused for 32 reactions with retention of 80% of its initial enzyme activity. Copyright © 2011 Elsevier B.V. All rights reserved.

Printable Electrochemical Biosensors: A Focus on Screen-Printed Electrodes and Their Application

PubMed Central

Yamanaka, Keiichiro; Vestergaard, Mun’delanji C.; Tamiya, Eiichi

2016-01-01

In this review we present electrochemical biosensor developments, focusing on screen-printed electrodes (SPEs) and their applications. In particular, we discuss how SPEs enable simple integration, and the portability needed for on-field applications. First, we briefly discuss the general concept of biosensors and quickly move on to electrochemical biosensors. Drawing from research undertaken in this area, we cover the development of electrochemical DNA biosensors in great detail. Through specific examples, we describe the fabrication and surface modification of printed electrodes for sensitive and selective detection of targeted DNA sequences, as well as integration with reverse transcription-polymerase chain reaction (RT-PCR). For a more rounded approach, we also touch on electrochemical immunosensors and enzyme-based biosensors. Last, we present some electrochemical devices specifically developed for use with SPEs, including USB-powered compact mini potentiostat. The coupling demonstrates the practical use of printable electrode technologies for application at point-of-use. Although tremendous advances have indeed been made in this area, a few challenges remain. One of the main challenges is application of these technologies for on-field analysis, which involves complicated sample matrices. PMID:27775661

Novel ferrocene-anchored ZnO nanoparticle/carbon nanotube assembly for glucose oxidase wiring: application to a glucose/air fuel cell.

PubMed

Haddad, Raoudha; Mattei, Jean-Gabriel; Thery, Jessica; Auger, Aurélien

2015-06-28

Glucose oxidase (GOx) is immobilized on ZnO nanoparticle-modified electrodes. The immobilized glucose oxidase shows efficient mediated electron transfer with ZnO nanoparticles to which the ferrocenyl moiety is π-stacked into a supramolecular architecture. The constructed ZnO-Fc/CNT modified electrode exhibits high ferrocene surface coverage, preventing any leakage of the π-stacked ferrocene from the newly described ZnO hybrid nanoparticles. The use of the new architecture of ZnO supported electron mediators to shuttle electrons from the redox centre of the enzyme to the surface of the working electrode can effectively bring about successful glucose oxidation. These modified electrodes evaluated as a highly efficient architecture provide a catalytic current for glucose oxidation and are integrated in a specially designed glucose/air fuel cell prototype using a conventional platinum-carbon (Pt/C) cathode at physiological pH (7.0). The obtained architecture leads to a peak power density of 53 μW cm(-2) at 300 mV for the Nafion® based biofuel cell under "air breathing" conditions at room temperature.

Exploring the Electrical Conductivity of Cytochrome P450 by Nano-Electrode and Conductive Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Li, Debin; Gu, Jianhua; Chye, Yewhee; Lederman, David; Kabulski, Jarod; Gannett, Peter; Tracy, Timothy

2006-03-01

There is a growing interest in measuring the conductivity of electron-transfer proteins. The cytochrome P450 (CP450) enzymes represent an important class of heme-containing enzymes. Immobilizing CP450 enzymes on a surface can be used for studying a single enzyme with respect to electron transfer. The spin state of the heme iron can change upon binding of a substrate. In our experiment, CP450 (diameter ˜ 5 nm) has been bonded to a metal surface. Nano-electrodes (gap < 10 nm) were fabricated by defining a bridge via e-beam lithography and then breaking the junction by electromigration at low temperatures. We have examined the electronic properties of CP450 by itself and after binding CP450 with flurbiprofen. The room temperature I-V conductivity is reminiscent to cyclic voltammetry measurements, indicating the presence of strong ionic transfer. At lower temperatures (100 K) the I-V characteristics indicate electronic transport dominated by tunneling processes. The conductive AFM is an additional method used to examine the enzyme's electronic properties. The results from two methods will be discussed..

Enhanced response of a proteinase K-based conductometric biosensor using nanoparticles.

PubMed

Nouira, Wided; Maaref, Abderrazak; Elaissari, Hamid; Vocanson, Francis; Siadat, Maryam; Jaffrezic-Renault, Nicole

2014-07-23

Proteinases are involved in a multitude of important physiological processes, such as protein metabolism. For this reason, a conductometric enzyme biosensor based on proteinase K was developed using two types of nanoparticles (gold and magnetic). The enzyme was directly adsorbed on negatively charged nanoparticles and then deposited and cross-linked on a planar interdigitated electrode (IDE). The biosensor was characterized with bovine serum albumin (BSA) as a standard protein. Higher sensitivity was obtained using gold nanoparticles. The linear range for BSA determination was then from 0.5 to 10 mg/L with a maximum response of 154 µs. These results are greater than that found without any nanoparticles (maximum response of 10 µs). The limit of detection (LOD) was 0.3 mg/L. An inter-sensor reproducibility of 3.5% was obtained.

Role of the HoxZ subunit in the electron transfer pathway of the membrane-bound [NiFe]-hydrogenase from Ralstonia eutropha immobilized on electrodes.

PubMed

Sezer, Murat; Frielingsdorf, Stefan; Millo, Diego; Heidary, Nina; Utesch, Tillman; Mroginski, Maria-Andrea; Friedrich, Bärbel; Hildebrandt, Peter; Zebger, Ingo; Weidinger, Inez M

2011-09-01

The role of the diheme cytochrome b (HoxZ) subunit in the electron transfer pathway of the membrane-bound [NiFe]-hydrogenase (MBH) heterotrimer from Ralstonia eutropha H16 has been investigated. The MBH in its native heterotrimeric state was immobilized on electrodes and subjected to spectroscopic and electrochemical analysis. Surface enhanced resonance Raman spectroscopy was used to monitor the redox and coordination state of the HoxZ heme cofactors while concomitant protein film voltammetric measurements gave insights into the catalytic response of the enzyme on the electrode. The entire MBH heterotrimer as well as its isolated HoxZ subunit were immobilized on silver electrodes coated with self-assembled monolayers of ω-functionalized alkylthiols, displaying the preservation of the native heme pocket structure and an electrical communication between HoxZ and the electrode. For the immobilized MBH heterotrimer, catalytic reduction of the HoxZ heme cofactors was observed upon H(2) addition. The catalytic currents of MBH with and without the HoxZ subunit were measured and compared with the heterogeneous electron transfer rates of the isolated HoxZ. On the basis of the spectroscopic and electrochemical results, we conclude that the HoxZ subunit under these artificial conditions is not primarily involved in the electron transfer to the electrode but plays a crucial role in stabilizing the enzyme on the electrode. © 2011 American Chemical Society

Highly sensitive glucose sensors based on enzyme-modified whole-graphene solution-gated transistors

NASA Astrophysics Data System (ADS)

Zhang, Meng; Liao, Caizhi; Mak, Chun Hin; You, Peng; Mak, Chee Leung; Yan, Feng

2015-02-01

Noninvasive glucose detections are convenient techniques for the diagnosis of diabetes mellitus, which require high performance glucose sensors. However, conventional electrochemical glucose sensors are not sensitive enough for these applications. Here, highly sensitive glucose sensors are successfully realized based on whole-graphene solution-gated transistors with the graphene gate electrodes modified with an enzyme glucose oxidase. The sensitivity of the devices is dramatically improved by co-modifying the graphene gates with Pt nanoparticles due to the enhanced electrocatalytic activity of the electrodes. The sensing mechanism is attributed to the reaction of H2O2 generated by the oxidation of glucose near the gate. The optimized glucose sensors show the detection limits down to 0.5 μM and good selectivity, which are sensitive enough for non-invasive glucose detections in body fluids. The devices show the transconductances two orders of magnitude higher than that of a conventional silicon field effect transistor, which is the main reason for their high sensitivity. Moreover, the devices can be conveniently fabricated with low cost. Therefore, the whole-graphene solution-gated transistors are a high-performance sensing platform for not only glucose detections but also many other types of biosensors that may find practical applications in the near future.

Amplified electrochemiluminescence detection of DNA based on novel quantum dots signal probe by multiple cycling amplification strategy.

PubMed

Tan, Lu; Ge, Junjun; Jiao, Meng; Jie, Guifen; Niu, Shuyan

2018-06-01

In the present work, we designed a unique enzyme-aided multiple amplification strategy for sensitive electrochemiluminescence (ECL) detection of DNA by using the amplified gold nanoparticles (GNPS)-polyamidoamine (PAMAM)-CdSe quantum dots (QDs) signal probe. Firstly, the novel GNPS-PAMAM dendrimers nanostructure with good biocompatibility and electroconductibility contains many amino groups, which can load a large number of CdSe QDs to develop amplified ECL signal probe. Then, the presence of target DNA activated the enzyme-assisted polymerization strand-displacement cycling reaction, and a large number of the hairpin template was opened. Subsequently, the opened stem further interacted with the capture hairpin (HP) DNA on the electrode, and the GNPS-PAMAM-CdSe signal probe hybridized with the exposed stem of the HP to trigger the second new polymerization reaction. Meanwhile, the first cycle was generating abundant DNA triggers which could directly open the template. As a result of the cascade amplification technique, a large number of CdSe QDs signal probe could be assembled on the electrode, generating much amplified ECL signal for sensitive detection of target DNA. Thus, this novel QDs-based amplified ECL strategy holds great promise for DNA detection and can be further exploited for sensing applications in clinical diagnostics. Copyright © 2018 Elsevier B.V. All rights reserved.

Tyrosinase-Based Biosensors for Selective Dopamine Detection

PubMed Central

Florescu, Monica; David, Melinda

2017-01-01

A novel tyrosinase-based biosensor was developed for the detection of dopamine (DA). For increased selectivity, gold electrodes were previously modified with cobalt (II)-porphyrin (CoP) film with electrocatalytic activity, to act both as an electrochemical mediator and an enzyme support, upon which the enzyme tyrosinase (Tyr) was cross-linked. Differential pulse voltammetry was used for electrochemical detection and the reduction current of dopamine-quinone was measured as a function of dopamine concentration. Our experiments demonstrated that the presence of CoP improves the selectivity of the electrode towards dopamine in the presence of ascorbic acid (AA), with a linear trend of concentration dependence in the range of 2–30 µM. By optimizing the conditioning parameters, a separation of 130 mV between the peak potentials for ascorbic acid AA and DA was obtained, allowing the selective detection of DA. The biosensor had a sensitivity of 1.22 ± 0.02 µA·cm−2·µM−1 and a detection limit of 0.43 µM. Biosensor performances were tested in the presence of dopamine medication, with satisfactory results in terms of recovery (96%), and relative standard deviation values below 5%. These results confirmed the applicability of the biosensors in real samples such as human urine and blood serum. PMID:28590453

Highly sensitive glucose sensors based on enzyme-modified whole-graphene solution-gated transistors

PubMed Central

Zhang, Meng; Liao, Caizhi; Mak, Chun Hin; You, Peng; Mak, Chee Leung; Yan, Feng

2015-01-01

Noninvasive glucose detections are convenient techniques for the diagnosis of diabetes mellitus, which require high performance glucose sensors. However, conventional electrochemical glucose sensors are not sensitive enough for these applications. Here, highly sensitive glucose sensors are successfully realized based on whole-graphene solution-gated transistors with the graphene gate electrodes modified with an enzyme glucose oxidase. The sensitivity of the devices is dramatically improved by co-modifying the graphene gates with Pt nanoparticles due to the enhanced electrocatalytic activity of the electrodes. The sensing mechanism is attributed to the reaction of H2O2 generated by the oxidation of glucose near the gate. The optimized glucose sensors show the detection limits down to 0.5 μM and good selectivity, which are sensitive enough for non-invasive glucose detections in body fluids. The devices show the transconductances two orders of magnitude higher than that of a conventional silicon field effect transistor, which is the main reason for their high sensitivity. Moreover, the devices can be conveniently fabricated with low cost. Therefore, the whole-graphene solution-gated transistors are a high-performance sensing platform for not only glucose detections but also many other types of biosensors that may find practical applications in the near future. PMID:25655666

Amperometric Determination of Glucose at Parts per Million Levels with Immobilized Glucose Oxidase.

ERIC Educational Resources Information Center

Sittampalam, G.; Wilson, G. S.

1982-01-01

An experiment on the operation and utility of an amperometric immobilized enzyme electrode (or probe) is described, including advantages of the experiment, equipment, reagents, preparation of phosphate buffer, enzyme immobilization techniques, laboratory procedures, precautions, and discussion of experimental results. (SK)

Bio-inspired nanocatalysts for the oxygen reduction reaction.

PubMed

Grumelli, Doris; Wurster, Benjamin; Stepanow, Sebastian; Kern, Klaus

2013-01-01

Electrochemical conversions at fuel cell electrodes are complex processes. In particular, the oxygen reduction reaction has substantial overpotential limiting the electrical power output efficiency. Effective and inexpensive catalytic interfaces are therefore essential for increased performance. Taking inspiration from enzymes, earth-abundant metal centres embedded in organic environments present remarkable catalytic active sites. Here we show that these enzyme-inspired centres can be effectively mimicked in two-dimensional metal-organic coordination networks self-assembled on electrode surfaces. Networks consisting of trimesic acid and bis-pyridyl-bispyrimidine coordinating to single iron and manganese atoms on Au(111) effectively catalyse the oxygen reduction and reveal distinctive catalytic activity in alkaline media. These results demonstrate the potential of surface-engineered metal-organic networks for electrocatalytic conversions. Specifically designed coordination complexes at surfaces inspired by enzyme cofactors represent a new class of nanocatalysts with promising applications in electrocatalysis.

Extracellular Electron Uptake: Among Autotrophs and Mediated by Surfaces.

PubMed

Tremblay, Pier-Luc; Angenent, Largus T; Zhang, Tian

2017-04-01

Autotrophic microbes can acquire electrons from solid donors such as steel, other microbial cells, or electrodes. Based on this feature, bioprocesses are being developed for the microbial electrosynthesis (MES) of useful products from the greenhouse gas CO 2 . Extracellular electron-transfer mechanisms involved in the acquisition of electrons from metals by electrical microbially influenced corrosion (EMIC), from other living cells by interspecies electron transfer (IET), or from an electrode during MES rely on: (i) mediators such as H 2 ; (ii) physical contact through electron-transfer proteins; or (iii) mediator-generating enzymes detached from cells. This review explores the interactions of autotrophs with solid electron donors and their importance in nature and for biosustainable technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

ZnO/Cu nanocomposite: a platform for direct electrochemistry of enzymes and biosensing applications.

PubMed

Yang, Chi; Xu, Chunxiang; Wang, Xuemei

2012-03-06

Unique structured nanomaterials can facilitate the direct electron transfer between redox proteins and the electrodes. Here, in situ directed growth on an electrode of a ZnO/Cu nanocomposite was prepared by a simple corrosion approach, which enables robust mechanical adhesion and electrical contact between the nanostructured ZnO and the electrodes. This is great help to realize the direct electron transfer between the electrode surface and the redox protein. SEM images demonstrate that the morphology of the ZnO/Cu nanocomposite has a large specific surface area, which is favorable to immobilize the biomolecules and construct biosensors. Using glucose oxidase (GOx) as a model, this ZnO/Cu nanocomposite is employed for immobilization of GOx and the construction of the glucose biosensor. Direct electron transfer of GOx is achieved at ZnO/Cu nanocomposite with a high heterogeneous electron transfer rate constant of 0.67 ± 0.06 s(-1). Such ZnO/Cu nanocomposite provides a good matrix for direct electrochemistry of enzymes and mediator-free enzymatic biosensors.

Exploiting enzyme catalysis in ultra-low ion strength media for impedance biosensing of avian influenza virus using a bare interdigitated electrode.

PubMed

Fu, Yingchun; Callaway, Zachary; Lum, Jacob; Wang, Ronghui; Lin, Jianhan; Li, Yanbin

2014-02-18

Enzyme catalysis is broadly used in various fields but generally applied in media with high ion strength. Here, we propose the exploitation of enzymatic catalysis in ultra-low ion strength media to induce ion strength increase for developing a novel impedance biosensing method. Avian influenza virus H5N1, a serious worldwide threat to poultry and human health, was adopted as the analyte. Magnetic beads were modified with H5N1-specific aptamer to capture the H5N1 virus. This was followed by binding concanavalin A (ConA), glucose oxidase (GOx), and Au nanoparticles (AuNPs) to create bionanocomposites through a ConA-glycan interaction. The yielded sandwich complex was transferred to a glucose solution to trigger an enzymatic reaction to produce gluconic acid, which ionized to increase the ion strength of the solution, thus decreasing the impedance on a screen-printed interdigitated array electrode. This method took advantages of the high efficiency of enzymatic catalysis and the high susceptibility of electrochemical impedance on the ion strength and endowed the biosensor with high sensitivity and a detection limit of 8 × 10(-4) HAU in 200 μL sample, which was magnitudes lower than that of some analogues based on biosensing methods. Furthermore, the proposed method required only a bare electrode for measurements of ion strength change and had negligible change on the surficial properties of the electrode, though some modification of magnetic beads/Au nanoparticles and the construction of a sandwich complex were still needed. This helped to avoid the drawbacks of commonly used electrode immobilization methods. The merit for this method makes it highly useful and promising for applications. The proposed method may create new possibilities in the broad and well-developed enzymatic catalysis fields and find applications in developing sensitive, rapid, low-cost, and easy-to-operate biosensing and biocatalysis devices.

A needle-type sensor for monitoring glucose in whole blood.

PubMed

Yang, Q; Atanasov, P; Wilkins, E

1997-01-01

A new surface-process technology employing electrochemical fixation of a bioactive substance (enzyme and heparin) to a sensor electrode was developed to provide biocompatability and functionality. The fabrication process includes electroentrapment of glucose oxidase and heparin on a platinum electrode by using 1,3-phenylenediamine codeposition. Electrochemically grown 1,3-phenylenediamine was also used as the outer coating of the sensor's enzyme electrode in order to extend the linear range. The sensor shows a sensitivity of 3 nA/mM and a linear range from 40 to 400 mg/dL at 37 degrees C when tested in whole blood. This sensor is characterized by a fast response. The sensor shows a minimum change in its performance when stored inactive in buffer for 12 weeks. When tested at physiologic glucose levels, the sensor demonstrates satisfactory low interference from common interfering substances. This technology seems promising for the preparation of implantable intravascular biosensors.

Vertically aligned carbon nanotube probes for monitoring blood cholesterol

NASA Astrophysics Data System (ADS)

Roy, Somenath; Vedala, Harindra; Choi, Wonbong

2006-02-01

Detection of blood cholesterol is of great clinical significance. The amperometric detection technique was used for the enzymatic assay of total cholesterol. Multiwall carbon nanotubes (MWNTs), vertically aligned on a silicon platform, promote heterogeneous electron transfer between the enzyme and the working electrode. Surface modification of the MWNT with a biocompatible polymer, polyvinyl alcohol (PVA), converted the hydrophobic nanotube surface into a highly hydrophilic one, which facilitates efficient attachment of biomolecules. The fabricated working electrodes showed a linear relationship between cholesterol concentration and the output signal. The efficacy of the multiwall carbon nanotubes in promoting heterogeneous electron transfer was evident by distinct electrochemical peaks and higher signal-to-noise ratio as compared to the Au electrode with identical enzyme immobilization protocol. The selectivity of the cholesterol sensor in the presence of common interferents present in human blood, e.g. uric acid, ascorbic acid and glucose, is also reported.

Development of a Sensitive Electrochemical Enzymatic Reaction-Based Cholesterol Biosensor Using Nano-Sized Carbon Interdigitated Electrodes Decorated with Gold Nanoparticles

PubMed Central

Sharma, Deepti; Lee, Jongmin; Seo, Junyoung; Shin, Heungjoo

2017-01-01

We developed a versatile and highly sensitive biosensor platform. The platform is based on electrochemical-enzymatic redox cycling induced by selective enzyme immobilization on nano-sized carbon interdigitated electrodes (IDEs) decorated with gold nanoparticles (AuNPs). Without resorting to sophisticated nanofabrication technologies, we used batch wafer-level carbon microelectromechanical systems (C-MEMS) processes to fabricate 3D carbon IDEs reproducibly, simply, and cost effectively. In addition, AuNPs were selectively electrodeposited on specific carbon nanoelectrodes; the high surface-to-volume ratio and fast electron transfer ability of AuNPs enhanced the electrochemical signal across these carbon IDEs. Gold nanoparticle characteristics such as size and morphology were reproducibly controlled by modulating the step-potential and time period in the electrodeposition processes. To detect cholesterol selectively using AuNP/carbon IDEs, cholesterol oxidase (ChOx) was selectively immobilized via the electrochemical reduction of the diazonium cation. The sensitivity of the AuNP/carbon IDE-based biosensor was ensured by efficient amplification of the redox mediators, ferricyanide and ferrocyanide, between selectively immobilized enzyme sites and both of the combs of AuNP/carbon IDEs. The presented AuNP/carbon IDE-based cholesterol biosensor exhibited a wide sensing range (0.005–10 mM) and high sensitivity (~993.91 µA mM−1 cm−2; limit of detection (LOD) ~1.28 µM). In addition, the proposed cholesterol biosensor was found to be highly selective for the cholesterol detection. PMID:28914766

Immobilization of glucose oxidase onto a novel platform based on modified TiO2 and graphene oxide, direct electrochemistry, catalytic and photocatalytic activity.

PubMed

Haghighi, Nasibeh; Hallaj, Rahman; Salimi, Abdollah

2017-04-01

In this work a new organic-inorganic nanocomposite has been introduced for enzyme immobilization. The composite consisting of graphene oxide (GO) and titanium oxide nanoparticles (TiO 2 ) modified with 2, 2'-dithioxo-3, 3'-bis (3-(triethoxysilyl) propyl)-2H, 2'H-[5, 5'-bithiazolylidene]-4, 4'(3H, 3'H)-dione as Organic-Inorganic Supporting Ligand (OISL). The OISL was covalently attached to TiO 2 nanoparticles and employed for obtaining a suitable solid surface to enzyme attachment. The glucose oxidase (GOD) was irreversibly loaded on the GC/GO/TiO 2 -OISL using consecutive cyclic voltammetry. The enzyme immobilization and the enzymatic activity were determined by electrochemical methods. The cyclic voltammogram displayed a pair of well-defined and nearly symmetric redox peaks with a formal potential of -0.465V and an apparent electron transfer rate constant of 1.74s -1 . The GO/TiO 2 -OISL can catalyze the electroreduction and electrooxidation of hydrogen peroxide. The GC/GO/TiO 2 -OISL/GOD electrode was used in the hydrogen peroxide determination. The fabricated nanobiocomposite shows dramatic photoelectrocatalytic activity which evaluated by studying the electrocatalytic activity of the fabricated electrode toward hydrogen peroxide in darkness and in the presences of light. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an amperometric sulfite biosensor based on SO(x)/PBNPs/PPY modified ITO electrode.

PubMed

Rawal, Rachna; Pundir, C S

2012-11-01

A sulfite oxidase (SO(x)) (EC 1.8.3.1) purified from Syzygium cumini leaves was immobilized onto prussian blue nanoparticles/polypyrrole composite (PBNPs/PPY) electrodeposited onto the surface of indium tin oxide (ITO) electrode. An amperometric sulfite biosensor was fabricated using SO(x)/PBNPs/PPY/ITO electrode as working electrode, Ag/AgCl as standard and Pt wire as auxiliary electrode connected through a potentiostat. The working electrode was characterized by Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) before and after immobilization of SO(x). The biosensor showed optimum response within 2s, when operated at 20 mV s⁻¹ in 0.1M Tris-HCl buffer, pH 8.5 and at 35 °C. Linear range and minimum detection limit were 0.5-1000 μM and 0.12 μM (S/N=3) respectively. There was good correlation (r=0.99) between red wine samples sulfite value by standard DTNB method and the present method. The sensor was evaluated with 97% recovery of added sulfite in red wine samples and 2.2% and 4.3% within and between batch coefficients of variation respectively. The sensor was employed for determination of sulfite level in red and white wine samples. The enzyme electrode was used 200 times over a period of 3 months when stored at 4 °C. Copyright © 2012 Elsevier B.V. All rights reserved.

Enzymatic biofuel cell based on electrodes modified with lipid liquid-crystalline cubic phases

NASA Astrophysics Data System (ADS)

Nazaruk, Ewa; Smoliński, Sławomir; Swatko-Ossor, Marta; Ginalska, Grażyna; Fiedurek, Jan; Rogalski, Jerzy; Bilewicz, Renata

Two glassy carbon electrodes modified with enzymes embedded in lyotropic liquid-crystalline cubic phase were used for the biofuel cell construction. The monoolein liquid-crystalline film allowed to avoid separators in the biofuel cell. Glucose and oxygen as fuels, and glucose oxidase and laccase as anode and cathode biocatalysts, respectively were used. The biofuel cell parameters were examined in McIlvaine buffer, pH 7 solution containing 15 mM of glucose and saturated with dioxygen. A series of mediators were tested taking into account their formal potentials, stability in the cubic phase and efficiency of mediation. Most stable was the biofuel cell based on tetrathiafulvalene (TTF) and 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as anode and cathode mediators, respectively. The open-circuit voltage was equal to 450 ± 40 mV. The power densities and current densities were measured for all the systems studied.

Electrochemistry in diabetes management.

PubMed

Heller, Adam; Feldman, Ben

2010-07-20

Diabetes devastates lives and burdens society. Hypoglycemic (low glucose) episodes cause blackouts, and severe ones are life-threatening. Periods of hyperglycemia (high glucose) cause circulatory disease, stroke, amputations, blindness, kidney failure and nerve degeneration. In this Account, we describe the founding of TheraSense, now a major part of Abbott Diabetes Care, and the development of two products that have improved the lives of people with diabetes. The first, a virtually painless microcoulometer (300 nL volume), the FreeStyle blood glucose monitoring system, was approved by the FDA and became available in 2000. In 2009, this system was used in more than one billion blood assays. The second, the enzyme-wiring based, subcutaneously-implanted FreeStyle Navigator continuous glucose monitoring system, was approved by the FDA and became available in the United States in 2008. The strips of the FreeStyle blood glucose monitoring system comprise a printed parallel plate coulometer, with a 50 microm gap between two facing printed electrodes, a carbon electrode and a Ag/AgCl electrode. The volume of blood between the facing plates is accurately controlled. The glucose is electrooxidized through catalysis by a glucose dehydrogenase (GDH) and an Os(2+/3+) redox mediator, which is reduced by the glucose-reduced enzyme and is electrooxidized on the carbon electrode. Initially the system used pyrroloquinoline quinone (PQQ)-dependent GDH but now uses flavin adenine dinucleotide (FAD)-dependent GDH. Because the facing electrodes are separated by such a small distance, shuttling of electrons by the redox couple could interfere with the coulometric assay. However, the Os(2+/3+) redox mediator is selected to have a substantially negative formal potential, between 0.0 and -0.2 V, versus that of the facing Ag/AgCl electrode. This makes the flow of a shuttling current between the two electrodes virtually impossible because the oxidized Os(3+) complex cannot be appreciably reduced at the more positively poised Ag/AgCl electrode. The FreeStyle Navigator continuous glucose monitoring system uses a subcutaneously implanted miniature plastic sensor connected to a transmitter to measure glycemia amperometrically and sends the information to a PDA-like device every minute. The sensor consists of a narrow (0.6 mm wide) plastic substrate on which carbon-working, Ag/AgCl reference, and carbon counter electrodes are printed in a stacked geometry. The active wired enzyme sensing layer covers only about 0.1 mm(2) of the working electrode and is overlaid by a flux-limiting membrane. It resides at about 5 mm depth in the subcutaneous adipose tissue and monitors glucose concentrations over the range 20-500 mg/dL. Its core component, a miniature, disposable, amperometric glucose sensor, has an electrooxidation catalyst made from a crosslinked adduct of glucose oxidase (GOx) and a GOx wiring redox hydrogel containing a polymer-bound Os(2+/3+) complex. Because of the selectivity of the catalyst for glucose, very little current flows in the absence of glucose. That feature, either alone or in combination with other features of the sensor, facilitates the one-point calibration of the system. The sensor is implanted subcutaneously and replaced by the patient after 5 days use with minimal pain. The wearer does not feel its presence under the skin.

Asymmetric Nanopore Electrode-Based Amplification for Electron Transfer Imaging in Live Cells.

PubMed

Ying, Yi-Lun; Hu, Yong-Xu; Gao, Rui; Yu, Ru-Jia; Gu, Zhen; Lee, Luke P; Long, Yi-Tao

2018-04-25

Capturing real-time electron transfer, enzyme activity, molecular dynamics, and biochemical messengers in living cells is essential for understanding the signaling pathways and cellular communications. However, there is no generalizable method for characterizing a broad range of redox-active species in a single living cell at the resolution of cellular compartments. Although nanoelectrodes have been applied in the intracellular detection of redox-active species, the fabrication of nanoelectrodes to maximize the signal-to-noise ratio of the probe remains challenging because of the stringent requirements of 3D fabrication. Here, we report an asymmetric nanopore electrode-based amplification mechanism for the real-time monitoring of NADH in a living cell. We used a two-step 3D fabrication process to develop a modified asymmetric nanopore electrode with a diameter down to 90 nm, which allowed for the detection of redox metabolism in living cells. Taking advantage of the asymmetric geometry, the above 90% potential drop at the two terminals of the nanopore electrode converts the faradaic current response into an easily distinguishable bubble-induced transient ionic current pattern. Therefore, the current signal was amplified by at least 3 orders of magnitude, which was dynamically linked to the presence of trace redox-active species. Compared to traditional wire electrodes, this wireless asymmetric nanopore electrode exhibits a high signal-to-noise ratio by increasing the current resolution from nanoamperes to picoamperes. The asymmetric nanopore electrode achieves the highly sensitive and selective probing of NADH concentrations as low as 1 pM. Moreover, it enables the real-time nanopore monitoring of the respiration chain (i.e., NADH) in a living cell and the evaluation of the effects of anticancer drugs in an MCF-7 cell. We believe that this integrated wireless asymmetric nanopore electrode provides promising building blocks for the future imaging of electron transfer dynamics in live cells.

Martian Superoxide and Peroxide O2 Release (OR) Assay: A New Technology for Terrestrial and Planetary Applications

NASA Technical Reports Server (NTRS)

Georgiou, Christos D.; Zisimopoulos, Dimitrios; Panagiotidis, Konstantinos; Grintzalis, Kontantinos; Papapostolou, Ioannis; Quinn, Richard C.; McKay, Christopher P.; Sun, Henry J.

2015-01-01

This study presents an assay for the detection and quantification of soil metal superoxides and peroxides in regolith and soil. The O2 release (OR) assay is based on the enzymatic conversion of the hydrolysis products of metal oxides to O2, and their quantification by an O2 electrode based on the stoichiometry of the involved reactions: The intermediate product O2 from the hydrolysis of metal superoxides is converted by cytochrome c to O2, and also by superoxide dismutase (SOD) to 1/2 mol O2 and 1/2 mol H2O2, which is then converted by catalase (CAT) to 1/2 mol O2. The product H2O2 from the hydrolysis of metal peroxides and hydroperoxides is converted to 1/2 mol O2 by CAT. The assay-method was validated in a sealed sample chamber using a liquid-phase Clark-type O2 electrode with known concentrations of O2 and H2O2, and with commercial metal superoxide and peroxide mixed with Mars analogue Mojave and Atacama Desert soils. Carbonates and perchlorates, both present on Mars, do not interfere with the assay. The assay lower limit of detection, using luminescence quenching/optical sensing O2-electrodes, is 1 nmol O2 cm(exp. -3) or better. The activity of the assay enzymes SOD and cytochrome c was unaffected up to 6 Gy exposure by gamma-radiation, while CAT retained 100% and 40% of its activity at 3 and 6 Gy, respectively, demonstrating the suitability of these enzymes for planetary missions, e.g., in Mars or Europa.

Multiwalled carbon nanotube coated polyester fabric as textile based flexible counter electrode for dye sensitized solar cell.

PubMed

Arbab, Alvira Ayoub; Sun, Kyung Chul; Sahito, Iftikhar Ali; Qadir, Muhammad Bilal; Jeong, Sung Hoon

2015-05-21

Textile wearable electronics offers the combined advantages of both electronics and textile characteristics. The essential properties of these flexible electronics such as lightweight, stretchable, and wearable power sources are in strong demand. Here, we have developed a facile route to fabricate multi walled carbon nanotube (MWCNT) coated polyester fabric as a flexible counter electrode (CE) for dye sensitized solar cells (DSSCs). A variety of MWCNT and enzymes with different structures were used to generate individual enzyme-dispersed MWCNT (E-MWCNT) suspensions by non-covalent functionalization. A highly concentrated colloidal suspension of E-MWCNT was deposited on polyester fabric via a simple tape casting method using an air drying technique. In view of the E-MWCNT coating, the surface structure is represented by topologically randomly assembled tubular graphene units. This surface morphology has a high density of colloidal edge states and oxygen-containing surface groups which execute multiple catalytic sites for iodide reduction. A highly conductive E-MWCNT coated fabric electrode with a surface resistance of 15 Ω sq(-1) demonstrated 5.69% power conversion efficiency (PCE) when used as a flexible CE for DSSCs. High photo voltaic performance of our suggested system of E-MWCNT fabric-based DSSCs is associated with high sheet conductivity, low charge transfer resistance (RCT), and excellent electro catalytic activity (ECA). Such a conductive fabric demonstrated stable conductivity against bending cycles and strong mechanical adhesion of E-MWCNT on polyester fabric. Moreover, the polyester fabric is hydrophobic and, therefore, has good sealing capacity and retains the polymer gel electrolyte without seepage. This facile E-MWCNT fabric CE configuration provides a concrete fundamental background towards the development of textile-integrated solar cells.

Martian Superoxide and Peroxide O2 Release (OR) Assay: A New Technology for Terrestrial and Planetary Applications.

PubMed

Georgiou, Christos D; Zisimopoulos, Dimitrios; Panagiotidis, Konstantinos; Grintzalis, Konstantinos; Papapostolou, Ioannis; Quinn, Richard C; McKay, Christopher P; Sun, Henry J

2016-02-01

This study presents an assay for the detection and quantification of soil metal superoxides and peroxides in regolith and soil. The O2 release (OR) assay is based on the enzymatic conversion of the hydrolysis products of metal oxides to O2 and their quantification by an O2 electrode based on the stoichiometry of the involved reactions. The intermediate product O₂˙⁻ from the hydrolysis of metal superoxides is converted by cytochrome c to O2 and by superoxide dismutase (SOD) to ½ mol O2 and ½ mol H2O2, which is then converted by catalase (CAT) to ½ mol O2. The product H2O2 from the hydrolysis of metal peroxides and hydroperoxides is converted to ½ mol O2 by CAT. The assay method was validated in a sealed sample chamber by using a liquid-phase Clark-type O2 electrode with known concentrations of O₂˙⁻ and H2O2, and commercial metal superoxide and peroxide mixed with Mars analog Mojave and Atacama Desert soils. Carbonates and perchlorates, both present on Mars, do not interfere with the assay. The assay lower limit of detection, when using luminescence quenching/optical sensing O2-electrodes, is 1 nmol O2 cm(-3) or better. The activity of the assay enzymes SOD and cytochrome c was unaffected up to 6 Gy exposure by γ radiation, while CAT retained 100% and 40% of its activity at 3 and 6 Gy, respectively, which demonstrates the suitability of these enzymes for planetary missions, for example, on Mars or Europa.

Substrate specificity and interferences of a direct-electron-transfer-based glucose biosensor.

PubMed

Felice, Alfons K G; Sygmund, Christoph; Harreither, Wolfgang; Kittl, Roman; Gorton, Lo; Ludwig, Roland

2013-05-01

Electrochemical sensors for glucose monitoring employ different signal transduction strategies for electron transfer from the biorecognition element to the electrode surface. We present a biosensor that employs direct electron transfer and evaluate its response to various interfering substances known to affect glucose biosensors. The enzyme cellobiose dehydrogenase (CDH) was adsorbed on the surface of a carbon working electrode and covalently bound by cross linking. The response of CDH-modified electrodes to glucose and possible interfering compounds was measured by flow-injection analysis, linear sweep, and chronoamperometry. Chronoamperometry showed initial swelling/wetting of the electrode. After stabilization, the signal was stable and a sensitivity of 0.21 µA mM-1 cm-2 was obtained. To investigate the influence of the interfering substances on the biorecognition element, the simplest possible sensor architecture was used. The biosensor showed little (<5% signal deviation) or no response to various reported electroactive or otherwise interfering substances. Direct electron transfer from the biorecognition element to the electrode is a new principle applied to glucose biosensors, which can be operated at a low polarization potential of -100 mV versus silver/silver chloride. The reduction of interferences by electrochemically active substances is an attractive feature of this promising technology for the development of continuous glucose biosensors. © 2013 Diabetes Technology Society.

Integrated nanoparticle-biomolecule systems for biosensing and bioelectronics.

PubMed

Willner, Itamar; Baron, Ronan; Willner, Bilha

2007-04-15

The similar dimensions of biomolecules such as enzymes, antibodies or DNA, and metallic or semiconductor nanoparticles (NPs) enable the synthesis of biomolecule-NP hybrid systems where the unique electronic, photonic and catalytic properties of NPs are combined with the specific recognition and biocatalytic properties of biomolecules. The unique functions of biomolecule-NP hybrid systems are discussed with several examples: (i) the electrical contacting of redox enzymes with electrodes is the basis for the development of enzymatic electrodes for amperometric biosensors or biofuel cell elements. The reconstitution of the apo-glucose oxidase or apo-glucose dehydrogenase on flavin adenine dinucleotide (FAD)-functionalized Au NPs (1.4 nm) associated with electrodes, or on pyrroloquinoline quinone (PQQ)-functionalized Au NPs (1.4 nm) associated with electrodes, respectively, yields electrically contacted enzyme electrodes. The aligned, reconstituted enzymes on the electrode surfaces reveal effective electrical contacting, and the glucose oxidase and glucose dehydrogenase reveal turnover rates of 5000 and 11,800 s(-1), respectively. (ii) The photoexcitation of semiconductor nanoparticles yields fluorescence with a wavelength controlled by the size of the NPs. The fluorescence functions of semiconductor NPs are used to develop a fluorescence resonance energy transfer (FRET) assay for nucleic acids, and specifically, for analyzing telomerase activity in cancer cells. CdSe-ZnS NPs are functionalized by a primer recognized by telomerase, and this is elongated by telomerase extracted from HeLa cancer cells in the presence of dNTPs and Texas-red-functionalized dUTP. The dye integrated into the telomers allows the FRET process that is intensified as telomerization proceeds. Also, the photoexcited electron-hole pair generated in semiconductor NPs is used to generate photocurrents in a CdS-DNA hybrid system associated with an electrode. A redox-active intercalator, methylene blue, was incorporated into a CdS-duplex DNA monolayer associated with a Au electrode, and this facilitated the electron transfer between the electrode and the CdS NPs. The direction of the photocurrent was controlled by the oxidation state of the intercalator. (iii) Biocatalysts grow metallic NPs, and the absorbance of the NPs provides a means to assay the biocatalytic transformations. This is exemplified with the glucose oxidase-induced growth of Au NPs and with the tyrosinase-stimulated growth of Au NPs, in the presence of glucose or tyrosine, respectively. The biocatalytic growth of the metallic NPs is used to grow nanowires on surfaces. Glucose oxidase or alkaline phosphatase functionalized with Au NPs (1.4 nm) acted as 'biocatalytic inks' for the synthesis of metallic nanowires. The deposition of the Au NP-modified glucose oxidase, or the Au NP-modified alkaline phosphatase on Si surfaces by dip-pen nanolithography led to biocatalytic templates, that after interaction with glucose/AuCl4- or p-aminophenolphosphate/Ag+, allowed the synthesis of Au nanowires or Ag nanowires, respectively.

Potentiometric glucose biosensor based on core-shell Fe3O4-enzyme-polypyrrole nanoparticles.

PubMed

Yang, Zhengpeng; Zhang, Chunjing; Zhang, Jianxin; Bai, Wanbei

2014-01-15

Core-shell Fe3O4-enzyme-polypyrrole (Ppy) nanoparticles with excellent magnetism and conductivity were successfully prepared via the surface modification and enzyme self-encapsulation within Ppy. A novel potentiometric glucose biosensor has been constructed by effectively attaching the proposed Fe3O4-enzyme-Ppy nanoparticles to the surface of the magnetic glassy carbon electrode (MGCE). The optimum biosensing conditions could be provided with polymerization time of pyrrole for 6h and 0.42 mg immobilization amount of Fe3O4-enzyme-Ppy nanoparticles on MGCE. The performance of the developed glucose biosensor was evaluated and the results indicated that a sensitive glucose biosensor could be fabricated. The obtained glucose biosensor presents shorter response time (6 s), wider linear range (0.5 μM to 34 mM), lower limit of detection (LOD, 0.3 μM), high-selectivity monitoring of glucose and good stability (with about 98.1% of the initial response signal retained after 20 days). The analytical application of the glucose biosensor confirms the feasibility of glucose detection in serum sample. © 2013 Elsevier B.V. All rights reserved.

Detection of Ca2+-induced acetylcholine released from leukemic T-cells using an amperometric microfluidic sensor.

PubMed

Akhtar, Mahmood H; Hussain, Khalil K; Gurudatt, N G; Shim, Yoon-Bo

2017-12-15

A microfluidic structured-dual electrodes sensor comprising of a pair of screen printed carbon electrodes was fabricated to detect acetylcholine, where one of them was used for an enzyme reaction and another for a detection electrode. The former was coated with gold nanoparticles and the latter with a porous gold layer, followed by electropolymerization of 2, 2:5,2-terthiophene-3-(p-benzoic acid) (pTTBA) on both the electrodes. Then, acetylcholinesterase was covalently attached onto the reaction electrode, and hydrazine and choline oxidase were co-immobilized on the detection electrode. The layers of both modified electrodes were characterized employing voltammetry, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and quartz crystal microscopy. After the modifications of both electrode surfaces, they were precisely faced each other to form a microfluidic channel structure, where H 2 O 2 produced from the sequential enzymatic reactions was reduced by hydrazine to obtain the analytical signal which was analyzed by the detection electrode. The microfluidic sensor at the optimized experimental conditions exhibited a wide dynamic range from 0.7nM to 1500μM with the detection limit of 0.6 ± 0.1nM based on 3s (S/N = 3). The biomedical application of the proposed sensor was evaluated by detecting acetylcholine in human plasma samples. Moreover, the Ca 2+ -induced acetylcholine released in leukemic T-cells was also investigated to show the in vitro detection ability of the designed microfluidic sensor. Interference due to the real component matrix were also studied and long term stability of the designed sensor was evaluated. The analytical performance of the designed sensor was also compared with commercially available ACh detection kit. Copyright © 2017 Elsevier B.V. All rights reserved.

Silicon/SU8 multi-electrode micro-needle for in vivo neurochemical monitoring.

PubMed

Vasylieva, Natalia; Marinesco, Stéphane; Barbier, Daniel; Sabac, Andrei

2015-10-15

Simultaneous monitoring of glucose and lactate is an important challenge for understanding brain energetics in physiological or pathological states. We demonstrate here a versatile method based on a minimally invasive single implantation in the rat brain. A silicon/SU8-polymer multi-sensing needle-shaped biosensor, was fabricated and tested. The multi-electrode array design comprises three platinum planar microelectrodes with a surface area of 40 × 200 µm(2) and a spacing of 200 µm, which were micromachined on a single 3mm long micro-needle having a 100 × 50 µm(2) cross-section for reduced tissue damage during implantation. Platinum micro-electrodes were aligned at the bottom of micro-wells obtained by photolithography on a SU8 photoresist layer. After clean room processing, each micro-electrode was functionalized inside the micro-wells by means of a micro-dispensing device, either with glucose oxidase or with lactate oxidase, which were cross-linked on the platinum electrodes. The third electrode covered with Bovine Serum Albumin (BSA) was used for the control of non-specific currents. The thick SU8 photoresist layer has revealed excellent electrical insulation of the micro-electrodes and between interconnection lines, and ensured a precise localization and packaging of the sensing enzymes on platinum micro-electrodes. During in vitro calibration with concentrations of analytes in the mM range, the micro-wells patterned in the SU8 photoresist proved to be highly effective in eliminating cross-talk signals, caused by H2O2 diffusion from closely spaced micro-electrodes. Moreover, our biosensor was successfully assayed in the rat cortex for simultaneous monitoring of both glucose and lactate during insulin and glucose administration. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of a Portable Multi-Analyte Biosensor for Organic Acid Determination in Silage.

PubMed

Pilas, Johanna; Yazici, Yasemen; Selmer, Thorsten; Keusgen, Michael; Schöning, Michael J

2018-05-08

Multi-analyte biosensors may offer the opportunity to perform cost-effective and rapid analysis with reduced sample volume, as compared to electrochemical biosensing of each analyte individually. This work describes the development of an enzyme-based biosensor system for multi-parametric determination of four different organic acids. The biosensor array comprises five working electrodes for simultaneous sensing of ethanol, formate, d-lactate, and l-lactate, and an integrated counter electrode. Storage stability of the biosensor was evaluated under different conditions (stored at +4 °C in buffer solution and dry at −21 °C, +4 °C, and room temperature) over a period of 140 days. After repeated and regular application, the individual sensing electrodes exhibited the best stability when stored at −21 °C. Furthermore, measurements in silage samples (maize and sugarcane silage) were conducted with the portable biosensor system. Comparison with a conventional photometric technique demonstrated successful employment for rapid monitoring of complex media.

Application of a Portable Multi-Analyte Biosensor for Organic Acid Determination in Silage

PubMed Central

Pilas, Johanna; Yazici, Yasemen; Selmer, Thorsten; Keusgen, Michael

2018-01-01

Multi-analyte biosensors may offer the opportunity to perform cost-effective and rapid analysis with reduced sample volume, as compared to electrochemical biosensing of each analyte individually. This work describes the development of an enzyme-based biosensor system for multi-parametric determination of four different organic acids. The biosensor array comprises five working electrodes for simultaneous sensing of ethanol, formate, d-lactate, and l-lactate, and an integrated counter electrode. Storage stability of the biosensor was evaluated under different conditions (stored at +4 °C in buffer solution and dry at −21 °C, +4 °C, and room temperature) over a period of 140 days. After repeated and regular application, the individual sensing electrodes exhibited the best stability when stored at −21 °C. Furthermore, measurements in silage samples (maize and sugarcane silage) were conducted with the portable biosensor system. Comparison with a conventional photometric technique demonstrated successful employment for rapid monitoring of complex media. PMID:29738487

An improved biosensor for acetaldehyde determination using a bienzymatic strategy at poly(neutral red) modified carbon film electrodes.

PubMed

Ghica, Mariana Emilia; Pauliukaite, Rasa; Marchand, Nicolas; Devic, Eric; Brett, Christopher M A

2007-05-15

Improved biosensors for acetaldehyde determination have been developed using a bienzymatic strategy, based on a mediator-modified carbon film electrode and co-immobilisation of NADH oxidase and aldehyde dehydrogenase. Modification of the carbon film electrode with poly(neutral red) mediator resulted in a sensitive, low-cost and reliable NADH detector. Immobilisation of the enzymes was performed using encapsulation in a sol-gel matrix or cross-linking with glutaraldehyde. The bienzymatic biosensors were characterized by studying the influence of pH, applied potential and co-factors. The sol-gel and glutaraldehyde biosensors showed a linear response up to 60 microM and 100 microM, respectively, with detection limits of 2.6 microM and 3.3 microM and sensitivities were 1.7 microA mM(-1) and 5.6 microA mM(-1). The optimised biosensors showed good stability and good selectivity and have been tested for application for the determination of acetaldehyde in natural samples such as wine.

Urea impedimetric biosensing using electrospun nanofibers modified with zinc oxide nanoparticles

NASA Astrophysics Data System (ADS)

Migliorini, Fernanda L.; Sanfelice, Rafaela C.; Mercante, Luiza A.; Andre, Rafaela S.; Mattoso, Luiz H. C.; Correa, Daniel. S.

2018-06-01

Reliable analytical techniques to evaluate dairy products, including milk, are of outmost importance to ensure food safety against contaminants. Among possible substances employed as adulterants in milk, urea raises deep concern due to its harmful effects to consumer's health. In the present study, a biosensing platform was developed to be applied in the electrochemical detection of urea. The sensing platform was fabricated using polymeric electrospun nanofibers of polyamide 6 (PA6) and polypyrrole (PPy) deposited onto fluorine doped tin oxide (FTO) electrodes, which were then modified with zinc oxide nanoparticles (ZnO). This material showed excellent properties for the immobilization of urease enzyme, conferring the FTO/PA6/PPy/ZnO/urease electrode high sensitivity for urea detection within the concentration range between 0.1 and 250 mg dL-1 with a limit of detection of 0.011 mg dL-1. The results achieved evidence the potential of electrospun nanofibers-based electrodes for applications in biosensors aiming at dairy products analysis.

Molybdenum disulphide and graphene quantum dots as electrode modifiers for laccase biosensor.

PubMed

Vasilescu, Ioana; Eremia, Sandra A V; Kusko, Mihaela; Radoi, Antonio; Vasile, Eugeniu; Radu, Gabriel-Lucian

2016-01-15

A nanocomposite formed from molybdenum disulphide (MoS2) and graphene quantum dots (GQDs) was proposed as a novel and suitable support for enzyme immobilisation displaying interesting electrochemical properties. The conductivity of the carbon based screen-printed electrodes was highly improved after modification with MoS2 nanoflakes and GQDs, the nanocomposite also providing compatible matrix for laccase immobilisation. The influence of different modification steps on the final electroanalytical performances of the modified electrode were evaluated by UV-vis absorption and fluorescence spectroscopy, scanning electron microscopy, transmission electron microscopy, X ray diffraction, electrochemical impedance spectroscopy and cyclic voltammetry. The developed laccase biosensor has responded efficiently to caffeic acid over a concentration range of 0.38-100µM, had a detection limit of 0.32µM and a sensitivity of 17.92nAµM(-1). The proposed analytical tool was successfully applied for the determination of total polyphenolic content from red wine samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

PubMed Central

Alvarado-Gámez, Ana Lorena; Alonso-Lomillo, María Asunción; Domínguez-Renedo, Olga; Arcos-Martínez, María Julia

2014-01-01

A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 μM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water. PMID:24569772

Direct Electron Transfer of Dehydrogenases for Development of 3rd Generation Biosensors and Enzymatic Fuel Cells.

PubMed

Bollella, Paolo; Gorton, Lo; Antiochia, Riccarda

2018-04-24

Dehydrogenase based bioelectrocatalysis has been increasingly exploited in recent years in order to develop new bioelectrochemical devices, such as biosensors and biofuel cells, with improved performances. In some cases, dehydrogeases are able to directly exchange electrons with an appropriately designed electrode surface, without the need for an added redox mediator, allowing bioelectrocatalysis based on a direct electron transfer process. In this review we briefly describe the electron transfer mechanism of dehydrogenase enzymes and some of the characteristics required for bioelectrocatalysis reactions via a direct electron transfer mechanism. Special attention is given to cellobiose dehydrogenase and fructose dehydrogenase, which showed efficient direct electron transfer reactions. An overview of the most recent biosensors and biofuel cells based on the two dehydrogenases will be presented. The various strategies to prepare modified electrodes in order to improve the electron transfer properties of the device will be carefully investigated and all analytical parameters will be presented, discussed and compared.

Electrochemiluminescence detection of NADH and ethanol based on partial sulfonation of sol-gel network with gold nanoparticles.

PubMed

Deng, Liu; Zhang, Lihua; Shang, Li; Guo, Shaojun; Wen, Dan; Wang, Fuan; Dong, Shaojun

2009-03-15

We developed a stable, sensitive electrochemiluminescence (ECL) biosensor based on the synthesis of a new sol-gel material with the ion-exchange capacity sol-gel to coimmobilize the Ru(bpy)(3)(2+) and enzyme. The partial sulfonated (3-mercaptopropyl)-trimethoxysilane sol-gel (PSSG) film acted as both an ion exchanger for the immobilization of Ru(bpy)(3)(2+) and a matrix to immobilize gold nanoparticles (AuNPs). The AuNPs/PSSG/Ru(bpy)(3)(2+) film modified electrode allowed sensitive the ECL detection of NADH as low as 1 nM. Such an ability of AuNPs/PSSG/Ru(bpy)(3)(2+) film to promote the electron transfer between Ru(bpy)(3)(2+) and the electrode suggested a new, promising biocompatible platform for the development of dehydrogenase-based ECL biosensors. With alcohol dehydrogenase (ADH) as a model, we then constructed an ethanol biosensor, which had a linear range of 5 microM to 5.2 mM with a detection limit of 12nM.

Biosensors Fabricated through Electrostatic Assembly of Enzymes/Polyelectrolyte Hybrid Layers on Carbon Nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Yuehe; Liu, Guodong; Wang, Jun

2006-06-01

Carbon nanotubes (CNTs) have emerged as new class of nanomaterials that is receiving considerable interest because of their unique structure, mechanical, and electronic properties. One promising application of CNTs is to fabricate highly sensitive chemo/biosensors.1-4 For construction of these CNT-based sensors, the CNTs first have to be modified with some molecules specific to the interests. Generally, covalent binding, affinity, and electrostatic interaction have been utilized for the modification of CNTs. Among them, the electrostatic method is attractive due to its simplicity and high efficiency. In present work, we have developed highly sensitively amperometric biosensors for glucose, choline, organophosphate pesticide (OPP)more » and nerve agents (NAs) based on electrostatically assembling enzymes on the surface of CNTs. All these biosensors were fabricated by immobilization of enzymes on the negatively charged CNTs surface through alternately assembling a cationic poly(diallydimethylammonium chloride) (PDDA) layer and an enzyme layer. Using this layer-by-layer (LBL) technique, a bioactive nanocomposite film was fabricated on the electrode surface. Owing to the electrocatalytic effect of CNTs, an amplified electrochemical signal was achieved, which leads to low detections limits for glucose, choline, and OPP and NAs.« less

Paper-based maskless enzymatic sensor for glucose determination combining ink and wire electrodes.

PubMed

Amor-Gutiérrez, O; Costa Rama, E; Costa-García, A; Fernández-Abedul, M T

2017-07-15

In this work we have developed an amperometric enzymatic biosensor in a paper-based platform with a mixed electrode configuration: carbon ink for the working electrode (WE) and metal wires (from a low-cost standard electronic connection) for reference (RE) and auxiliary electrodes (AE). A hydrophobic wax-defined paper area was impregnated with diluted carbon ink. Three gold-plated pins of the standard connection are employed, one for connecting the WE and the other two acting as RE and AE. The standard connection works as a clip in order to support the paper in between. As a proof-of-concept, glucose sensing was evaluated. The enzyme cocktail (glucose oxidase, horseradish peroxidase and potassium ferrocyanide as mediator of the electron transfer) was adsorbed on the surface. After drying, glucose solution was added to the paper, on the opposite side of the carbon ink. It wets RE and AE, and flows by capillarity through the paper contacting the carbon WE surface. The reduction current of ferricyanide, product of the enzymatic reaction, is measured chronoamperometrically and correlates to the concentration of glucose. Different parameters related to the bioassay were optimized, adhering the piece of paper onto a conventional screen-printed carbon electrode (SPCE). In this way, the RE and the AE of the commercial card were employed for optimizing the paper-WE. After evaluating the assay system in the hybrid paper-SPCE cell, the three-electrode system consisting of paper-WE, wire-RE and wire-AE, was employed for glucose determination, achieving a linear range between 0.3 and 15mM with good analytical features and being able of quantifying glucose in real food samples. Copyright © 2016 Elsevier B.V. All rights reserved.

[Biosensor development in clinical analysis].

PubMed

Boitieux, J L; Desmet, G; Thomas, D

1985-01-01

The use of enzymes immobilized or as markers formed the subject of more than thousand publications in the field of industry or biomedical applications, during the last five years. Recently, some authors published works concerning immobilization of total microorganisms for catalytic purposes, others use the enzymatic activity for marking molecules involved in immunological analysis processes. Together industrial biotechnology and medical analysis laboratory are interested with the evolution of these procedures involving the activity of immobilized enzymes. Enzyme immobilization allowed the lowering of analysis costs for, in this case, the enzyme can be used several times. We take account of the two main cases which are encountered during utilization of immobilized enzymes of analytical purposes. The enzyme is used directly for the catalysed reaction or it is used as enzymatic marker. These both aspects are developed mainly for the elaboration of enzymatic and immunoenzymatic electrodes and the realization of automatic computerized devices allowing continuous estimation of numerous biological blood parameters. From these two precise examples, glucose and antigen determination, the authors show the evolution of these technologies in the field of immobilized enzymes or captors and the analysis of signals given by these electrodes requiring a computerized treatment. This new technology opens to important potentialities in the analytical field. The automatization of these devices allowing the control in real time, will probably make easier the optimization steps of procedures actually used in the biomedical sphere.

Application of gas diffusion electrodes in bioelectrochemical syntheses and energy conversion.

PubMed

Horst, Angelika E W; Mangold, Klaus-Michael; Holtmann, Dirk

2016-02-01

Combining the advantages of biological components (e.g., reaction specificity, self-replication) and electrochemical techniques in bioelectrochemical systems offers the opportunity to develop novel efficient and sustainable processes for the production of a number of valuable products. The choice of electrode material has a great impact on the performance of bioelectrochemical systems. In addition to the redox process at the electrodes, interactions of biocatalysts with electrodes (e.g., enzyme denaturation or biofouling) need to be considered. In recent years, gas diffusion electrodes (GDEs) have proved to be very attractive electrodes for bioelectrochemical purposes. GDEs are porous electrodes, that posses a large three-phase boundary surface. At this interface, a solid catalyst supports the electrochemical reaction between gaseous and liquid phase. This mini-review discusses the application of GDEs in microbial and enzymatic fuel cells, for microbial electrolysis, in biosensors and for electroenzymatic synthesis reactions. © 2015 Wiley Periodicals, Inc.

Biosensor based on Butyrylcholinesterase for Detection of Carbofuran

NASA Astrophysics Data System (ADS)

Dey, Mousumi; Bhuvanagayathri, R.; Daniel, David K.

2015-04-01

Esterase enzymes play an important role in biology because they are responsible for the hydrolysis of choline esters. In their absence, the original state of the post synaptic membranes cannot be reestablished. Therefore, the aim of the work is to study the inhibiting action exerted by the group of compounds on these enzymes. Among these class of inhibiting compounds, pesticides are important because of the potential danger as a result of their large scale use in agriculture. Pesticides are generally determined using liquid or gas chromatography methods with various detection techniques. These methods are very sensitive and discriminating, however they require sample pretreatment such as extraction, preconcentration and clean up, which are skilled techniques and high cost treatment and also time consuming. In this study, acetyl cholinesterase and butyrylcholinesterase based biosensors have emerged as a promising tool for the detection and characterization of pesticides which are inhibitors of these enzymes. Although the physiological function of butyrylcholinesterase in comparison with acetyl cholinesterase is ambiguous, it has larger substrate specificity towards choline esters. Therefore, the development of a more selective electrode against choline, can lead to more sensitive determination of the inhibitor being investigated. Hence in the present work, a method based on inhibition of butyrylcholinesterase was attempted for quantification of carbofuran on the basis of cholinesterase inhibition. Butyrylcholinesterase with an activity of 10.2 units/mg was immobilized on a solid surface by cross linking with glutaraldehyde. The immobilized system was calibrated by correlating the inhibition of the butyrylcholinesterase activity with varying concentrations of the butyryl choline chloride and carbofuran. The sensing mechanism was investigated for its response to carbofuran concentrations ranging from 125 to 1,000 ppm. The effects of butyryl choline chloride concentration on the response of the sensing strip were also determined. Through this work, a sensing element made up of a carbon based electrode, containing the immobilized butyrylcholinesterase, has been described. This element has certain practical advantages like smaller size, user friendly, easy portability and disposability.

Amperometric biosensors based on deposition of gold and platinum nanoparticles on polyvinylferrocene modified electrode for xanthine detection.

PubMed

Baş, Salih Zeki; Gülce, Handan; Yıldız, Salih; Gülce, Ahmet

2011-12-15

In this study, new xanthine biosensors, XO/Au/PVF/Pt and XO/Pt/PVF/Pt, based on electroless deposition of gold(Au) and platinum(Pt) nanoparticles on polyvinylferrocene(PVF) coated Pt electrode for detection of xanthine were presented. The amperometric responses of the enzyme electrodes were measured at the constant potential, which was due to the electrooxidation of enzymatically produced H(2)O(2). Compared with XO/PVF/Pt electrode, XO/Au/PVF/Pt and XO/Pt/PVF/Pt exhibited excellent electrocatalytic activity towards the oxidation of the analyte. Effect of Au and Pt nanoparticles was investigated by monitoring the response currents at the different deposition times and the different concentrations of KAuCl(4) and PtBr(2). Under the optimal conditions, the calibration curves of XO/Au/PVF/Pt and XO/Pt/PVF/Pt were obtained over the range of 2.5 × 10(-3) to 0.56 mM and 2.0 × 10(-3) to 0.66 mM, respectively. The detection limits were 7.5 × 10(-4)mM for XO/Au/PVF/Pt and 6.0 × 10(-4)mM for XO/Pt/PVF/Pt. The effects of interferents, the operational and the storage stabilities of the biosensors and the applicabilities of the proposed biosensors to the drug samples analysis were also evaluated. Copyright © 2011 Elsevier B.V. All rights reserved.

para-Sulfonatocalix[6]arene-modified silver nanoparticles electrodeposited on glassy carbon electrode: preparation and electrochemical sensing of methyl parathion.

PubMed

Bian, Yinghui; Li, Chunya; Li, Haibing

2010-05-15

In this paper, a new electrochemical sensor, based on modified silver nanoparticles, was fabricated using one-step electrodeposition approach. The para-sulfonatocalix[6]arene-modified silver nanoparticles coated on glassy carbon electrode (pSC(6)-Ag NPs/GCE) was characterized by attenuated total reflection IR spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), etc. The pSC(6) as the host are highly efficient to capture organophosphates (OPs), which dramatically facilitates the enrichment of nitroaromatic OPs onto the electrochemical sensor surface. The combination of the host-guest supramolecular structure and the excellent electrochemical catalytic activities of the pSC(6)-Ag NPs/GCE provides a fast, simple, and sensitive electrochemical method for detecting nitroaromatic OPs. In this work, methyl parathion (MP) was used as a nitroaromatic OP model for testing the proposed sensor. In comparison with Ag NPs-modified electrode, the cathodic peak current of MP was amplified significantly. Differential pulse voltammetry was used for the simultaneous determination of MP. Under optimum conditions, the current increased linearly with the increasing concentration of MP in the range of 0.01-80microM, with a detection limit of 4.0nM (S/N=3). The fabrication reproducibility and stability of the sensor is better than that of enzyme-based electrodes. The possible underlying mechanism is discussed.

Method to detect the end-point for PCR DNA amplification using an ionically labeled probe and measuring impedance change

DOEpatents

Miles, Robin R [Danville, CA; Belgrader, Phillip [Severna Park, MD; Fuller, Christopher D [Oakland, CA

2007-01-02

Impedance measurements are used to detect the end-point for PCR DNA amplification. A pair of spaced electrodes are located on a surface of a microfluidic channel and an AC or DC voltage is applied across the electrodes to produce an electric field. An ionically labeled probe will attach to a complementary DNA segment, and a polymerase enzyme will release the ionic label. This causes the conductivity of the solution in the area of the electrode to change. This change in conductivity is measured as a change in the impedance been the two electrodes.

Electrochemical magnetoimmunosensing approach for the sensitive detection of H9N2 avian influenza virus particles.

PubMed

Zhou, Chuan-Hua; Shu, Yun; Hong, Zheng-Yuan; Pang, Dai-Wen; Zhang, Zhi-Ling

2013-09-01

A novel electrochemical magnetoimmunosensor for fast and ultrasensitive detection of H9N2 avian influenza virus particles (H9N2 AIV) was designed based on the combination of high-efficiency immunomagnetic separation, enzyme catalytic amplification, and the biotin-streptavidin system. The reusable, homemade magneto Au electrode (M-AuE) was designed and used for the direct sensing. Immunocomplex-coated magnetic beads (IMBs) were easily accumulated on the surface of the M-AuE to obtain the catalytically reduced electrochemical signal of H2 O2 after the immunoreaction. The transducer was regenerated through a simple washing procedure, which made it possible to detect all the samples on a single electrode with higher reproducibility. The magnetic-bead-based electrochemical immunosensor showed better analytical performance than the planar-electrode-based immunosensor with the same sandwich construction. Amounts as low as 10 pg mL(-1) H9N2 AIV could be detected even in samples of chicken dung. This electrochemical magnetoimmunosensor not only provides a simple platform for the detection of the virus with high sensitivity, selectivity, and reproducibility but also shows great potential in the early diagnosis of diseases. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical nonenzymatic sensing of glucose using advanced nanomaterials.

PubMed

Dhara, Keerthy; Mahapatra, Debiprosad Roy

2017-12-13

An overview (with 376 refs.) is given here on the current state of methods for electrochemical sensing of glucose based on the use of advanced nanomaterials. An introduction into the field covers aspects of enzyme based sensing versus nonenzymatic sensing using nanomaterials. The next chapter cover the most commonly used nanomaterials for use in such sensors, with sections on uses of noble metals, transition metals, metal oxides, metal hydroxides, and metal sulfides, on bimetallic nanoparticles and alloys, and on other composites. A further section treats electrodes based on the use of carbon nanomaterials (with subsections on carbon nanotubes, on graphene, graphene oxide and carbon dots, and on other carbonaceous nanomaterials. The mechanisms for electro-catalysis are also discussed, and several Tables are given where the performance of sensors is being compared. Finally, the review addresses merits and limitations (such as the frequent need for working in strongly etching alkaline solutions and the need for diluting samples because sensors often have analytical ranges that are far below the glucose levels found in blood). We also address market/technology gaps in comparison to commercially available enzymatic sensors. Graphical Abstract Schematic representation of electrochemical nonenzymatic glucose sensing on the nanomaterials modified electrodes. At an applied potential, the nanomaterial-modified electrodes exhibit excellent electrocatalytic activity for direct oxidation of glucose oxidation.

Influence of different nanoparticles on electrochemical behavior of glucose biosensor

NASA Astrophysics Data System (ADS)

Nenkova, R. D.; Ivanov, Y. L.; Godjevargova, T. I.

2017-02-01

The influence of nanosized particles on the glucose oxidase loading and the performance of amperometric glucose bionsensors were studied. Four enzyme electrodes (Pt/PAN/GOD, Pt/PAN/NZ/GOD, Pt/PAN/NZ/MNP/GOD, Pt/PAN/NZ/MWNT/GOD) were prepared by cross-linking of glucose oxidase (GOD) on nanocomposite material. Nanocomposites were prepared by entrapping nanozeolite (NZ), multiwalled carbon nanotubes (MWNT) and magnetic nanoparticles (MNP) in polyacrylonitrile (PAN) film. Cyclic voltammetric kinetic studies have been carried out with the four biosensors and the surface concentration of the adsorbed electroactive species on the electrodes was estimated. The highest enzyme concentration on the electrode surface corresponded to the electrodes prepared by nanozeolite separate (Pt/PAN/NZ/GOD) and combined with multi-walled carbon nanotubes (Pt/PAN/NZ/MWNT/GOD). The sensitivity of these two biosensors was the highest and that is in accordance with the greater amount of the adsorbed electroactive species on the electrodes (0.373 mol.cm-2). This was indication that a good synergistic effect happened when MWNTs and NZ were combined and these greatly improve the electron transfer ability of the sensor interface. Amperometric measurement of the two glucose oxidase electrodes (Pt/PAN/NZ/GOD and Pt/PAN/NZ/MWNT/GOD) with best results was carried out. The linear concentration interval of the Pt/PAN/NZ/MWNT/GOD biosensor was up to 3 mM, the detection limit - 0.02 mM glucose and the storage stability - 81% of its initial current response after 30 days.

Enzymatic measurement of free and esterified cholesterol levels in plasma and other biological preparations using the oxygen electrode in a modified glucose analyzer.

PubMed

Dietschy, J M; Weeks, L E; Delente, J J

1976-12-01

A method is described for assaying free and esterified cholesterol using the oxygen electrode in a modified glucose analyzer to measure the relative amount of oxygen utilization taking place during oxydation of free cholesterol by the enzyme, cholesterol oxidase. A second enzyme, cholesterol ester hydrolase, is utilized to generate free cholesterol from cholesterol esters. This assay procedure is rapid, specific, reproducible and applicable to the measurement of free and esterified cholesterol carried in the major plasma lipoprotein fractions of man and the rat and, in addition, it can be utilized for the assay of sterols in subcellular fractions of cells.

Hierarchical meso/macro-porous carbon fabricated from dual MgO templates for direct electron transfer enzymatic electrodes.

PubMed

Funabashi, Hiroto; Takeuchi, Satoshi; Tsujimura, Seiya

2017-03-23

We designed a three-dimensional (3D) hierarchical pore structure to improve the current production efficiency and stability of direct electron transfer-type biocathodes. The 3D hierarchical electrode structure was fabricated using a MgO-templated porous carbon framework produced from two MgO templates with sizes of 40 and 150 nm. The results revealed that the optimal pore composition for a bilirubin oxidase-catalysed oxygen reduction cathode was a mixture of 33% macropores and 67% mesopores (MgOC 33 ). The macropores improve mass transfer inside the carbon material, and the mesopores improve the electron transfer efficiency of the enzyme by surrounding the enzyme with carbon.

Hierarchical meso/macro-porous carbon fabricated from dual MgO templates for direct electron transfer enzymatic electrodes

NASA Astrophysics Data System (ADS)

Funabashi, Hiroto; Takeuchi, Satoshi; Tsujimura, Seiya

2017-03-01

We designed a three-dimensional (3D) hierarchical pore structure to improve the current production efficiency and stability of direct electron transfer-type biocathodes. The 3D hierarchical electrode structure was fabricated using a MgO-templated porous carbon framework produced from two MgO templates with sizes of 40 and 150 nm. The results revealed that the optimal pore composition for a bilirubin oxidase-catalysed oxygen reduction cathode was a mixture of 33% macropores and 67% mesopores (MgOC33). The macropores improve mass transfer inside the carbon material, and the mesopores improve the electron transfer efficiency of the enzyme by surrounding the enzyme with carbon.

Electrochemical biosensors for biocontaminant detection consisting of carbon nanotubes, platinum nanoparticles, dendrimers, and enzymes.

PubMed

Siriviriyanun, Ampornphan; Imae, Toyoko; Nagatani, Naoki

2013-12-15

The presented approach provides the advanced development of effective, rapid, and versatile electrochemical sensors for a small amount of analytes on potential, cheap, and disposable printed chips. The electrocatalytic activity of this biosensor revealed the feasible detection of hydrogen peroxide at low potential (~0.09 V) and the detection of a biocontaminant inhibitor (organophosphorus pesticide) in a wide range of concentrations. This efficiency comes from the chemical immobilization of catalysts (Pt nanoparticles) and electron transfer-enlarging materials (carbon nanotubes) on an electrode. Especially, dendrimers raise the stable conjugation of enzymes (acetylcholinesterase/choline oxidase/peroxidase) as well as nanoparticles and carbon nanotubes on an electrode. Copyright © 2013 Elsevier Inc. All rights reserved.

Ethanol generation, oxidation and energy production in a cooperative bioelectrochemical system.

PubMed

Pagnoncelli, Kamila C; Pereira, Andressa R; Sedenho, Graziela C; Bertaglia, Thiago; Crespilho, Frank N

2018-08-01

Integrating in situ biofuel production and energy conversion into a single system ensures the production of more robust networks as well as more renewable technologies. For this purpose, identifying and developing new biocatalysts is crucial. Herein, is reported a bioelectrochemical system consisting of alcohol dehydrogenase (ADH) and Saccharomyces cerevisiae, wherein both function cooperatively for ethanol production and its bioelectrochemical oxidation. Here, it is shown that it is possible to produce ethanol and use it as a biofuel in a tandem manner. The strategy is to employ flexible carbon fibres (FCF) electrode that could adsorb both the enzyme and the yeast cells. Glucose is used as a substrate for the yeast for the production of ethanol, while the enzyme is used to catalyse the oxidation of ethanol to acetaldehyde. Regarding the generation of reliable electricity based on electrochemical systems, the biosystem proposed in this study operates at a low temperature and ethanol production is proportional to the generated current. With further optimisation of electrode design, we envision the use of the cooperative biofuel cell for energy conversion and management of organic compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

Functional design of electrolytic biosensor

NASA Astrophysics Data System (ADS)

Gamage Preethichandra, D. M.; Mala Ekanayake, E. M. I.; Onoda, M.

2017-11-01

A novel amperometric biosensbased on conjugated polypyrrole (PPy) deposited on a Pt modified ITO (indium tin oxide) conductive glass substrate and their performances are described. We have presented a method of developing a highly sensitive and low-cost nano-biosensor for blood glucose measurements. The fabrication method proposed decreases the cost of production significantly as the amount of noble metals used is minimized. A nano-corrugated PPy substrate was developed through pulsed electrochemical deposition. The sensitivity achieved was 325 mA/(Mcm2) and the linear range of the developed sensor was 50-60 mmol/l. Then the application of the electrophoresis helps the glucose oxidase (GOx) on the PPy substrate. The main reason behind this high enzyme loading is the high electric field applied across the sensor surface (working electrode) and the counter electrode where that pushes the nano-scale enzyme particles floating in the phosphate buffer solution towards the substrate. The novel technique used has provided an extremely high sensitivities and very high linear ranges for enzyme (GOx) and therefore can be concluded that this is a very good technique to load enzyme onto the conducting polymer substrates.

Direct comparison of the performance of a bio-inspired synthetic nickel catalyst and a [NiFe]-hydrogenase, both covalently attached to electrodes.

PubMed

Rodriguez-Maciá, Patricia; Dutta, Arnab; Lubitz, Wolfgang; Shaw, Wendy J; Rüdiger, Olaf

2015-10-12

The active site of hydrogenases has been a source of inspiration for the development of molecular catalysts. However, direct comparisons between molecular catalysts and enzymes have not been possible because different techniques are used to evaluate both types of catalysts, minimizing our ability to determine how far we have come in mimicking the enzymatic performance. The catalytic properties of the [Ni(P(Cy) 2 N(Gly) 2 )2 ](2+) complex with the [NiFe]-hydrogenase from Desulfovibrio vulgaris immobilized on a functionalized electrode were compared under identical conditions. At pH 7, the enzyme shows higher activity and lower overpotential with better stability, while at low pH, the molecular catalyst outperforms the enzyme in all respects. This is the first direct comparison of enzymes and molecular complexes, enabling a unique understanding of the benefits and detriments of both systems, and advancing our understanding of the utilization of these bio-inspired complexes in fuel cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Disposable Organophosphorus Pesticides Enzyme Biosensor Based on Magnetic Composite Nano-Particles Modified Screen Printed Carbon Electrode

PubMed Central

Gan, Ning; Yang, Xin; Xie, Donghua; Wu, Yuanzhao; Wen, Weigang

2010-01-01

A disposable organophosphorus pesticides (OPs) enzyme biosensor based on magnetic composite nanoparticle-modified screen printed carbon electrodes (SPCE) has been developed. Firstly, an acetylcholinesterase (AChE)-coated Fe3O4/Au (GMP) magnetic nanoparticulate (GMP-AChE) was synthesized. Then, GMP-AChE was absorbed on the surface of a SPCE modified by carbon nanotubes (CNTs)/nano-ZrO2/prussian blue (PB)/Nafion (Nf) composite membrane by an external magnetic field. Thus, the biosensor (SPCE│CNTs/ZrO2/PB/Nf│GMP-AChE) for OPs was fabricated. The surface of the biosensor was characterized by scanning electron micrography (SEM) and X-ray fluorescence spectrometery (XRFS) and its electrochemical properties were studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The degree of inhibition (A%) of the AChE by OPs was determined by measuring the reduction current of the PB generated by the AChE-catalyzed hydrolysis of acetylthiocholine (ATCh). In pH = 7.5 KNO3 solution, the A was related linearly to the concentration of dimethoate in the range from 1.0 × 10−3–10 ng·mL−1 with a detection limit of 5.6 × 10−4 ng·mL−1. The recovery rates in Chinese cabbage exhibited a range of 88%–105%. The results were consistent with the standard gas chromatography (GC) method. Compared with other enzyme biosensors the proposed biosensor exhibited high sensitivity, good selectivity with disposable, low consumption of sample. In particular its surface can be easily renewed by removal of the magnet. The convenient, fast and sensitive voltammetric measurement opens new opportunities for OPs analysis. PMID:22315558

Covalent Attachment of the Water-insoluble Ni(P Cy 2 N Phe 2 ) 2 Electrocatalyst to Electrodes Showing Reversible Catalysis in Aqueous Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodríguez-Maciá, Patricia; Priyadarshani, Nilusha; Dutta, Arnab

Hydrogenases are a diverse group of metalloenzymes which catalyze the reversible conversion between molecular hydrogen and protons at high rates. The catalytic activity of these enzymes does not require overpotential because their active site has been evolutionarily optimized to operate fast and efficiently. These enzymes have inspired the development of molecular catalysts, which have dramatically improved in efficiency in recent years, to the point that some synthetic catalysts even outperform hydrogenases under certain conditions. In this work, we use a reversible noble-metal-free homogeneous catalyst, the [Ni(PCy2NPhe2)2]2+ complex, and we covalently immobilize it on a functionalized highly oriented pyrolytic graphite “edge”more » (HOPGe) electrode surface. This catalyst is not water soluble, but once it is surface-confined on the electrode, it maintains its catalytic properties in aqueous solutions, showing reversibility for H2 oxidation/reduction. Immobilization of the [Ni(PCy2NPhe2)2]2+ complex onto a multi-walled carbon nanotubes coated electrode leads to even higher catalytic current densities and enhanced stability.« less

Amperometric cholesterol biosensor based on in situ reconstituted cholesterol oxidase on an immobilized monolayer of flavin adenine dinucleotide cofactor.

PubMed

Vidal, Juan-C; Espuelas, Javier; Castillo, Juan-R

2004-10-01

A new amperometric biosensor for determining cholesterol based on deflavination of the enzyme cholesterol oxidase (ChOx) and subsequent reconstitution of the apo-protein with a complexed flavin adenine dinucleotide (FAD) monolayer is described. The charge transfer mediator pyrroquinoline quinone (PQQ) was covalently bound to a cystamine self-assembled monolayer (SAM) on an Au electrode. Boronic acid (BA) was then bound to PQQ using the carbodiimide procedure, and the BA ligand was complexed to the FAD molecules on which the apo-ChOx was subsequently reconstituted. The effective release of the FAD from the enzyme and the successful reconstitution were verified using molecular fluorescence and cyclic voltammetry. The optimal orientation of FAD toward the PQQ mediator and the distances between FAD and PQQ and between PQQ and electrode enhance the charge transfer, very high sensitivity (about 2,500 nAmM(-1)cm(-2)) being obtained for cholesterol determination. The biosensor is selective toward electroactive interferents (ascorbic acid and uric acid) and was tested in reference serum samples, demonstrating excellent accuracy (relative errors below 3% in all cases). The biosensor activity can be successfully regenerated in a simple process by successive reconstitution with batches of recently prepared apo-ChOx on the same immobilized Au/SAM-PQQ-BA-FAD monolayer (it was tested five times); the lifetime of the biosensor is about 45-60 days.

Electrochemical current rectification-a novel signal amplification strategy for highly sensitive and selective aptamer-based biosensor.

PubMed

Feng, Lingyan; Sivanesan, Arumugam; Lyu, Zhaozi; Offenhäusser, Andreas; Mayer, Dirk

2015-04-15

Electrochemical aptamer-based (E-AB) sensors represent an emerging class of recently developed sensors. However, numerous of these sensors are limited by a low surface density of electrode-bound redox-oligonucleotides which are used as probe. Here we propose to use the concept of electrochemical current rectification (ECR) for the enhancement of the redox signal of E-AB sensors. Commonly, the probe-DNA performs a change in conformation during target binding and enables a nonrecurring charge transfer between redox-tag and electrode. In our system, the redox-tag of the probe-DNA is continuously replenished by solution-phase redox molecules. A unidirectional electron transfer from electrode via surface-linked redox-tag to the solution-phase redox molecules arises that efficiently amplifies the current response. Using this robust and straight-forward strategy, the developed sensor showed a substantial signal amplification and consequently improved sensitivity with a calculated detection limit of 114nM for ATP, which was improved by one order of magnitude compared with the amplification-free detection and superior to other previous detection results using enzymes or nanomaterials-based signal amplification. To the best of our knowledge, this is the first demonstration of an aptamer-based electrochemical biosensor involving electrochemical rectification, which can be presumably transferred to other biomedical sensor systems. Copyright © 2014 Elsevier B.V. All rights reserved.

An amperometric bienzymatic cholesterol biosensor based on functionalized graphene modified electrode and its electrocatalytic activity towards total cholesterol determination.

PubMed

Manjunatha, Revanasiddappa; Shivappa Suresh, Gurukar; Melo, Jose Savio; D'Souza, Stanislaus F; Venkatesha, Thimmappa Venkatarangaiah

2012-09-15

Cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) have been covalently immobilized onto functionalized graphene (FG) modified graphite electrode. Enzymes modified electrodes were characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). FG accelerates the electron transfer from electrode surface to the immobilized ChOx, achieving the direct electrochemistry of ChOx. A well defined redox peak was observed, corresponding to the direct electron transfer of the FAD/FADH(2) of ChOx. The electron transfer coefficient (α) and electron transfer rate constant (K(s)) were calculated and their values are found to be 0.31 and 0.78 s(-1), respectively. For the free cholesterol determination, ChOx-FG/Gr electrode exhibits a sensitive response from 50 to 350 μM (R=-0.9972) with a detection limit of 5 μM. For total cholesterol determination, co-immobilization of ChEt and ChOx on modified electrode, i.e. (ChEt/ChOx)-FG/Gr electrode showed linear range from 50 to 300 μM (R=-0.9982) with a detection limit of 15 μM. Some common interferents like glucose, ascorbic acid and uric acid did not cause any interference, due to the use of a low operating potential. The FG/Gr electrode exhibits good electrocatalytic activity towards hydrogen peroxide (H(2)O(2)). A wide linear response to H(2)O(2) ranging from 0.5 to 7 mM (R=-0.9967) with a sensitivity of 443.25 μA mM(-1) cm(-2) has been obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of immobilization conditions on the properties of β-galactosidase immobilized in xanthan/chitosan multilayers

NASA Astrophysics Data System (ADS)

Yovcheva, T.; Vasileva, T.; Viraneva, A.; Cholev, D.; Bodurov, I.; Marudova, M.; Bivolarski, V.; Iliev, I.

2017-01-01

The effect of lactose concentration on the activity of the immobilised enzyme β-galactosidase from Aspergillus niger has been evaluated, considering future applications for the production of galactooligosaccahrides with prebiotic potential. The following enzyme was immobilized in xanthan and chitosan polyelectrolyte multilayers (PEMs) deposited by dip coating method on polylactic acid positively corona charged pads. The pads were charged in a corona discharge system, consisting of a corona electrode (needle), a grounded plate, and a metal grid placed between them. Positive 5 kV voltage was applied to the corona electrode. 1 kV voltage of the same polarity as that of the corona electrode was applied to the grid. The chitosan layers were crosslinked with sodium tripolyphosphate (Na-TPP). The enzyme showed a temperature optimum at 50 °C and a pH optimum at 5.0. The immobilization was carried out over the different adsorption time and optimum conditions were determined. These results give insights for further optimization of transgalactosydase reactions in order to produce galactooligosaccharides with specific structure and having pronounced better prebiotic properties. For the determination of the surface morphology of the investigated samples an atomic force microscope was used and root mean square roughness was obtained.

Direct Electrochemical Addressing of Immobilized Alcohol Dehydrogenase for the Heterogeneous Bioelectrocatalytic Reduction of Butyraldehyde to Butanol.

PubMed

Schlager, S; Neugebauer, H; Haberbauer, M; Hinterberger, G; Sariciftci, N S

2015-03-01

Modified electrodes using immobilized alcohol dehydrogenase enzymes for the efficient electroreduction of butyraldehyde to butanol are presented as an important step for the utilization of CO 2 -reduction products. Alcohol dehydrogenase was immobilized, embedded in an alginate-silicate hybrid gel, on a carbon felt (CF) electrode. The application of this enzyme to the reduction of an aldehyde to an alcohol with the aid of the coenzyme nicotinamide adenine dinucleotide (NADH), in analogy to the final step in the natural reduction cascade of CO 2 to alcohol, has been already reported. However, the use of such enzymatic reductions is limited because of the necessity of providing expensive NADH as a sacrificial electron and proton donor. Immobilization of such dehydrogenase enzymes on electrodes and direct pumping of electrons into the biocatalysts offers an easy and efficient way for the biochemical recycling of CO 2 to valuable chemicals or alternative synthetic fuels. We report the direct electrochemical addressing of immobilized alcohol dehydrogenase for the reduction of butyraldehyde to butanol without consumption of NADH. The selective reduction of butyraldehyde to butanol occurs at room temperature, ambient pressure and neutral pH. Production of butanol was detected by using liquid-injection gas chromatography and was estimated to occur with Faradaic efficiencies of around 40 %.

Enzyme-linked electrochemical DNA ligation assay using magnetic beads.

PubMed

Stejskalová, Eva; Horáková, Petra; Vacek, Jan; Bowater, Richard P; Fojta, Miroslav

2014-07-01

DNA ligases are essential enzymes in all cells and have been proposed as targets for novel antibiotics. Efficient DNA ligase activity assays are thus required for applications in biomedical research. Here we present an enzyme-linked electrochemical assay based on two terminally tagged probes forming a nicked junction upon hybridization with a template DNA. Nicked DNA bearing a 5' biotin tag is immobilized on the surface of streptavidin-coated magnetic beads, and ligated product is detected via a 3' digoxigenin tag recognized by monoclonal antibody-alkaline phosphatase conjugate. Enzymatic conversion of napht-1-yl phosphate to napht-1-ol enables sensitive detection of the voltammetric signal on a pyrolytic graphite electrode. The technique was tested under optimal conditions and various situations limiting or precluding the ligation reaction (such as DNA substrates lacking 5'-phosphate or containing a base mismatch at the nick junction, or application of incompatible cofactor), and utilized for the analysis of the nick-joining activity of a range of recombinant Escherichia coli DNA ligase constructs. The novel technique provides a fast, versatile, specific, and sensitive electrochemical assay of DNA ligase activity.

A new self-assembled layer-by-layer glucose biosensor based on chitosan biopolymer entrapped enzyme with nitrogen doped graphene.

PubMed

Barsan, Madalina M; David, Melinda; Florescu, Monica; Ţugulea, Laura; Brett, Christopher M A

2014-10-01

The layer-by-layer (LbL) technique has been used for the construction of a new enzyme biosensor. Multilayer films containing glucose oxidase, GOx, and nitrogen-doped graphene (NG) dispersed in the biocompatible positively-charged polymer chitosan (chit(+)(NG+GOx)), together with the negatively charged polymer poly(styrene sulfonate), PSS(-), were assembled by alternately immersing a gold electrode substrate in chit(+)(NG+GOx) and PSS(-) solutions. Gravimetric monitoring during LbL assembly by an electrochemical quartz microbalance enabled investigation of the adsorption mechanism and deposited mass for each monolayer. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the LbL modified electrodes, in order to establish the contribution of each monolayer to the overall electrochemical properties of the biosensor. The importance of NG in the biosensor architecture was evaluated by undertaking a comparative study without NG in the chit layer. The GOx biosensor's analytical properties were evaluated by fixed potential chronoamperometry and compared with similar reported biosensors. The biosensor operates at a low potential of -0.2V vs., Ag/AgCl, exhibiting a high sensitivity of 10.5 μA cm(-2) mM(-1), and a detection limit of 64 μM. This study shows a simple approach in developing new biosensor architectures, combining the advantages of nitrogen-doped graphene with the LbL technique for enzyme immobilization. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of glucose sensors using gold nanoparticles modified diamond electrode

NASA Astrophysics Data System (ADS)

Fachrurrazie; Ivandini, T. A.; Wibowo, W.

2017-04-01

A glucose sensor was successfully developed by immobilizing glucose oxidase (GOx) at boron-doped diamond (BDD) electrodes. Prior to GOx immobilization, the BDD was modified with gold nanoparticles (AuNPs). To immobilize AuNPs, the gold surface was modified to nitrogen termination. The characterization of the electrode surface was performed using an X-ray photoelectron spectroscopy and a scanning electron microscope, while the electrochemical properties of the enzyme electrode were characterized using cyclic voltammetry. Cyclic voltammograms of the prepared electrode for D-glucose in phosphate buffer solution pH 7 showed a new reduction peak at +0.16 V. The currents of the peak were linear in the concentration range of 0.1 M to 0.9 M, indicated that the GOx-AuNP-BDD can be applied for electrochemical glucose detection.

Electrochemical Study and Characterization of an Amperometric Biosensor Based on the Immobilization of Laccase in a Nanostructure of TiO₂ Synthesized by the Sol-Gel Method.

PubMed

Romero-Arcos, Mariana; Garnica-Romo, Ma Guadalupe; Martínez-Flores, Héctor Eduardo

2016-07-07

Laccase amperometric biosensors were developed to detect the catechol compound. The laccase enzyme (LAC) immobilization was performed on nanostructures of (a) titania (TiO₂); (b) titania/Nafion (TiO₂/NAF) (both immobilized by the sol-gel method) and a third nanostructure, which consisted of a single biosensor composite of Nafion and laccase enzyme denoted as NAF/LAC. The Nafion was deposited on a graphite electrode and used to avoid "cracking" on the matrix. The TiO₂ particle size was an average of 66 nm. FTIR spectroscopy vibration modes of different composites were determined. The electrochemical behavior of the biosensor was studied using electrochemical spectroscopy (EIS) and cyclic voltammetry (CV). The biosensor based on TiO₂/NAF/LAC presented the best electro-chemical properties with regard to sensitivity, stability and detection limit after a period of 22 days.

Miniature enzyme-based electrodes for detection of hydrogen peroxide release from alcohol-injured hepatocytes.

PubMed

Matharu, Zimple; Enomoto, James; Revzin, Alexander

2013-01-15

Alcohol insult to the liver sets off a complex sequence of inflammatory and fibrogenic responses. There is increasing evidence that hepatocytes play a key role in triggering these responses by producing inflammatory signals such as cytokines and reactive oxygen species (ROS). In the present study, we employed a cell culture/biosensor platform consisting of electrode arrays integrated with microfluidics to monitor extracellular H(2)O(2), one of the major ROS types, produced by primary rat hepatocytes during alcohol injury. The biosensor consisted of hydrogel microstructures with entrapped horseradish peroxidase (HRP) immobilized on an array of miniature gold electrodes. These arrays of sensing electrodes were integrated into microfluidic devices and modified with collagen (I) to promote hepatocyte adhesion. Once seeded into the microfluidic devices, hepatocytes were exposed to 100 mM ethanol and the signal at the working electrode was monitored by cyclic voltammetry (CV) over the course of 4 h. The CV experiments revealed that hepatocytes secreted up to 1.16 μM H(2)O(2) after 3 h of stimulation. Importantly, when hepatocytes were incubated with antioxidants or alcohol dehydrogenase inhibitor prior to alcohol exposure, the H(2)O(2) signal was decreased by ~5-fold. These experiments further confirmed that the biosensor was indeed monitoring oxidative stress generated by the hepatocytes and also pointed to one future use of this technology for screening hepatoprotective effects of antioxidants.

Symposium on Biosensors

DTIC Science & Technology

1989-11-01

cherists because a new parameter; the refractive index of materials is an important in design as the chemistry of the absorbing or reacting layer ...redox electrode surfaces (the Sharp electrodes); use of enzymes in reactive layers to generate from neutral charge substrate species that can be...and natural and synthetic ionophores in monovalent and divalent ion sensors since 1965); use of selective layers to extract or partition species into

Copper@carbon coaxial nanowires synthesized by hydrothermal carbonization process from electroplating wastewater and their use as an enzyme-free glucose sensor.

PubMed

Zhao, Yuxin; He, Zhaoyang; Yan, Zifeng

2013-01-21

In the pursuit of electrocatalysts with great economic and ecological values for non-enzymatic glucose sensors, one-dimensional copper@carbon (Cu@C) core-shell coaxial nanowires (NWs) have been successfully prepared via a simple continuous flow wet-chemistry approach from electroplating wastewater. The as-obtained products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy and Raman spectroscopy. The electrocatalytic activity of the modified electrodes by Cu@C NWs towards glucose oxidation was investigated by cyclic voltammetry and chronoamperometry. It was found that the as-obtained Cu@C NWs showed good electrochemical properties and could be used as an electrochemical sensor for the detection of glucose molecules. Compared to the other electrodes including the bare Nafion/glassy carbon electrode (GCE) and several hot hybrid nanostructures modified GCE, a substantial decrease in the overvoltage of the glucose oxidation was observed at the Cu@C NWs electrodes with oxidation starting at ca. 0.20 V vs. Ag/AgCl (3 M KCl). At an applied potential of 0.65 V, Cu@C NWs electrodes had a high and reproducible sensitivity of 437.8 µA cm(-2) mM(-1) to glucose. Linear responses were obtained with a detection limit of 50 nM. More importantly, the proposed electrode also had good stability, high resistance against poisoning by chloride ion and commonly interfering species. These good analytical performances make Cu@C NWs promising for the future development of enzyme-free glucose sensors.

Observation of Single-Protein and DNA Macromolecule Collisions on Ultramicroelectrodes.

PubMed

Dick, Jeffrey E; Renault, Christophe; Bard, Allen J

2015-07-08

Single-molecule detection is the ultimate sensitivity in analytical chemistry and has been largely unavailable in electrochemical analysis. Here, we demonstrate the feasibility of detecting electrochemically inactive single biomacromolecules, such as enzymes, antibodies, and DNA, by blocking a solution redox reaction when molecules adsorb and block electrode sites. By oxidizing a large concentration of potassium ferrocyanide on an ultramicroelectrode (UME, radius ≤150 nm), time-resolved, discrete adsorption events of antibodies, enzymes, DNA, and polystyrene nanospheres can be differentiated from the background by their "footprint". Further, by assuming that the mass transport of proteins to the electrode surface is controlled mainly by diffusion, a size estimate using the Stokes-Einstein relationship shows good agreement of electrochemical data with known protein sizes.

Development of an amperometric biosensor based on acetylcholine esterase covalently bound to a new support material.

PubMed

Khayyami, M; Pérez Pita, M T; Peña Garcia, N; Johansson, G; Danielsson, B; Larsson, P O

1998-01-01

A new type of amperometric biosensor based on immobilised acetylcholine esterase was designed and constructed. The enzyme was immobilised on a flow-through working electrode, which was prepared from reticulated vitreous carbon (RVC) or from a composite material consisting of RVC and superporous agarose. The sensor was operated in FIA mode using acetylthiocholine as a substrate. The sensor responded to inhibitors such as paraoxon-10(-9) mol was detected by the sensor in a non-optimised configuration. The practical lifetime of the sensor was at least 1 month.

Polymeric bionanocomposite cast thin films with in situ laccase-catalyzed polymerization of dopamine for biosensing and biofuel cell applications.

PubMed

Tan, Yueming; Deng, Wenfang; Li, Yunyong; Huang, Zhao; Meng, Yue; Xie, Qingji; Ma, Ming; Yao, Shouzhuo

2010-04-22

We report here on the facile preparation of polymer-enzyme-multiwalled carbon nanotubes (MWCNTs) cast films accompanying in situ laccase (Lac)-catalyzed polymerization for electrochemical biosensing and biofuel cell applications. Lac-catalyzed polymerization of dopamine (DA) as a new substrate was examined in detail by UV-vis spectroscopy, cyclic voltammetry, quartz crystal microbalance, and scanning electron microscopy. Casting the aqueous mixture of DA, Lac and MWCNTs on a glassy carbon electrode (GCE) yielded a robust polydopamine (PDA)-Lac-MWCNTs/GCE that can sense hydroquinone with 643 microA mM(-1) cm(-2) sensitivity and 20-nM detection limit (S/N = 3). The DA substrate yielded the best biosensing performance, as compared with aniline, o-phenylenediamine, or o-aminophenol as the substrate for similar Lac-catalyzed polymerization. Casting the aqueous mixture of DA, glucose oxidase (GOx), Lac, and MWCNTs on a Pt electrode yielded a robust PDA-GOx-Lac-MWCNTs/Pt electrode that exhibits glucose-detection sensitivity of 68.6 microA mM(-1) cm(-2). In addition, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) was also coimmobilized to yield a PDA-Lac-MWCNTs-ABTS/GCE that can effectively catalyze the reduction of O(2), and it was successfully used as the biocathode of a membraneless glucose/O(2) biofuel cell (BFC) in pH 5.0 Britton-Robinson buffer. The proposed biomacromolecule-immobilization platform based on enzyme-catalyzed polymerization may be useful for preparing many other multifunctional polymeric bionanocomposites for wide applications.

Nickel-phendione complex covalently attached onto carbon nanotube/cross linked glucose dehydrogenase as bioanode for glucose/oxygen compartment-less biofuel cell

NASA Astrophysics Data System (ADS)

Korani, Aazam; Salimi, Abdollah; Hadadzadeh, Hasan

2015-05-01

Here, [Ni(phendion) (phen)]Cl2 complex, (phendion and phen are 1,10-phenanthroline-5,6-dione and 5-amino-1, 10-phenanthrolin) covalently attached onto carboxyl functionalized multi walls carbon nanotube modified glassy carbon electrode (GCE/MWCNTs-COOH) using solid phase interactions and combinatorial approaches.The attached [Ni(phendion) (phen)]Cl2 complex displays a surface controlled electrode process and it acts as an effective redox mediator for electrocatalytic oxidation of dihydronicotinamide adenine dinucleotide (NADH) at reduced overpotentials. With co-immobilization of glucose dehydrogenase enzyme (GDH) by crosslinking an effective biocatalyst for glucose oxidation designed. The onset potential and current density are -0.1 V versus Ag/AgCl electrode and 0.550 mA cm-2, which indicate the applicability of the proposed system as an efficient bioanode for biofuel cell (BFC) design. A GCE/MWCNTs modified with electrodeposited gold nanoparticles (AuNPs) as a platform for immobilization of bilirubin oxidase (BOD) and the prepared GCE/MWCNTs/AuNPs/BOD biocathode exhibits an onset potential of 0.56 V versus Ag/AgCl. The performance of the fabricated bioanode and biocathode in a membraneless enzyme based glucose/O2 biofuel cell is evaluated. The open circuit voltage of the cell and maximum current density are 520 mV and 0.233 mA cm-2, respectively, while maximum power density of 40 μWcm-2 achieves at voltage of 280 mV with stable output power after 24 h continues operation.

Maltodextrin-powered enzymatic fuel cell through a non-natural enzymatic pathway

NASA Astrophysics Data System (ADS)

Zhu, Zhiguang; Wang, Yiran; Minteer, Shelley D.; Percival Zhang, Y.-H.

Enzymatic fuel cells (EFCs) use a variety of fuels to generate electricity through oxidoreductase enzymes, such as oxidases or dehydrogenases, as catalysts on electrodes. We have developed a novel synthetic enzymatic pathway containing two free enzymes (maltodextrin phosphorylase and phosphoglucomutase) and one immobilized glucose-6-phosphate dehydrogenase that can utilize an oligomeric substrate maltodextrin for producing electrons mediated via a diaphorase and vitamin K 3 electron shuttle system. Three different enzyme immobilization approaches were compared based on electrostatic force entrapment, chemical cross-linking, and cross-linking with the aid of carbon nanotubes. At 10 mM glucose-6-phosphate (G6P) as a substrate concentration, the maximum power density of 0.06 mW cm -2 and retaining 42% of power output after 11 days were obtained through the method of chemical cross-linking with carbon nanotubes, approximately 6-fold and 3.5-fold better than those of the electrostatic force-based method, respectively. When changed to maltodextrin (degree of polymerization = 19) as the substrate, the EFC achieved a maximum power density of 0.085 mW cm -2. With the advantages of stable, low cost, high energy density, non-inhibitor to enzymes, and environmental friendly, maltodextrin is suggested to be an ideal fuel to power enzymatic fuel cells.

Glucose biosensor based on immobilization of glucose oxidase on a carbon paste electrode modified with microsphere-attached l-glycine.

PubMed

Donmez, Soner; Arslan, Fatma; Sarı, Nurşen; Hasanoğlu Özkan, Elvan; Arslan, Halit

2017-09-01

In the present study, a novel biosensor that is sensitive to glucose was prepared using the microspheres modified with (4-formyl-3-methoxyphenoxymethyl)polystyrene (FMPS) with l-glycine. Polymeric microspheres having Schiff bases were prepared from FMPS using the glycine condensation method. Glucose oxidase enzyme was immobilized onto modified carbon paste electrode by cross-linking with glutaraldehyde. Oxidation of enzymatically produced H 2 O 2 (+0.5 V vs. Ag/AgCl) was used for determination of glucose. Optimal temperature and pH were found as 50 °C and 8.0, respectively. The glucose biosensor showed a linear working range from 5.0 × 10 -4 to 1.0 × 10 -2 M, R 2 = 0.999. Storage and operational stability of the biosensor were also investigated. The biosensor gave perfect reproducible results after 20 measurements with 3.3% relative standard deviation. It also had good storage stability. © 2016 International Union of Biochemistry and Molecular Biology, Inc.

Electrochemical Performance of Glucose/Oxygen Biofuel Cells Based on Carbon Nanostructures.

PubMed

Koo, Min-Hye; Das, Gautam; Yoon, Hyon Hee

2016-03-01

The electrochemical performance of glucose/oxygen biofuel cells based on carbon nanostructures was investigated in the present study. Different types of carbon nanomaterials, including multi-walled carbon nanotubes (MWCNT), functionalized MWCNT (f-MWCNT), carbon nanofibers (CNF), and functionalized CNF (f-CNF) were examined for electrode fabrications. The anode for glucose/oxygen biofuel cells were prepared by sequential coating of carbon nanomaterials, charge transfer complex (CTC), glucose oxidase (GOx) and nafion membrane. The anode was then integrated with a bilirubin oxidase-immobilized cathode for the biofuel cell test. It was found that the electrochemical performance of the enzyme electrodes was remarkably enhanced by the amalgamation of carbon nanomaterials with the CTC. The biofuel cell with anode comprising of f-CNF and the cathode with MWCNT exhibited the best electrochemical performance with a maximum power density of 210 μW/cm2 at a cell voltage of 0.44 V for 20 mM glucose concentration, which is comparable with the best power density value reported earlier.

Enzyme-coated microelectrodes to monitor lactate production in a nanoliter microfluidic cell culture device

PubMed Central

Ges, Igor A.; Baudenbacher, Franz

2015-01-01

Monitoring the degree of anaerobic respiration of cells in high density microscale culture systems is an enabling key technology and essential for cell-based biosensors. We have fabricated and incorporated miniature amperometric lactate sensing electrodes with working areas from 3 to 5×10−2 mm2 into a microfluidic-based microscale cell culture system to measure the lactate production rate of fibroblasts in nanoliter volumes. Planar thin film platinum electrode arrays on glass substrates were spin coated with lactate oxidase and a protective Nafion layer. The lactate electrodes had a high enzymatic activity described by a Michaelis-Menten constant of 2.6±0.1 mM, a linear response in the range 0.01÷2.5mM and a sensitivity of 7.3×10−2mA/mM·cm2. A replica-molded polydimethylsiloxane (PDMS) microfluidic device with nanoliter sensing volumes was aligned and sealed to a glass substrate with the sensing electrodes. We trapped fibroblasts in the cell culture volume and measured the lactate production rate using a stop and flow protocol. The average lactate production rate was 0.011±0.0049mM/min. The lactate production was suppressed with the addition of 2-deoxy-D-glucose, which binds to hexokinase. The blocking of hexokinase prevents the generation of pyruvate, the intermittent substrate required for lactate production even in the presence of glucose. PMID:20566279

In situ detection of microbial c-type cytochrome based on intrinsic peroxidase-like activity using screen-printed carbon electrode.

PubMed

Wen, Junlin; He, Daigui; Yu, Zhen; Zhou, Shungui

2018-08-15

C-type cytochromes (c-cyts) facilitate microbial extracellular electron transfer and play critical roles in biogeochemical cycling, bioelectricity generation and bioremediation. In this study, a simple and effective method has been developed to detect microbial c-cyts by means of peroxidase mimetic reaction on screen-printed carbon electrode (SPCE). To this end, bacteria cells were immobilized onto the working electrode surface of SPCE by a simple drop casting. After introducing 3,3',5,5'-tetramethylbenzidine (TMB) solution, microbial c-cyts with peroxidase-like activity catalyze the oxidation of TMB in the presence of hydrogen peroxide. The oxidized TMB was electrochemically determined and the current signal was employed to calculate the c-cyts content. This electrochemical method is highly sensitive for microbial c-cyts with a low detection limit of 40.78 fmol and a wide detection range between 51.70 fmol and 6.64 pmol. Moreover, the proposed technique can be universally expanded to detect c-cyts in other bacteria species such as Fontibacter ferrireducens, Pseudomonas aeruginosa, Comamonas guangdongensis and Escherichia coli. Furthermore, the proposed method confers an in situ facile and quantitative c-cyts detection without any destructive sample preparations, complex electrode modifications and expensive enzyme- or metal particle- based signal amplification. The suggested method advances an intelligent strategy for in situ quantification of microbial c-cyts and consequently holds promising application potential in microbiology and environmental science. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparing cuprous oxide nanomaterials by electrochemical method for non-enzymatic glucose biosensor

NASA Astrophysics Data System (ADS)

Nguyen, Thu-Thuy; Huy, Bui The; Hwang, Seo-Young; Vuong, Nguyen Minh; Pham, Quoc-Thai; Nghia, Nguyen Ngoc; Kirtland, Aaron; Lee, Yong-Ill

2018-05-01

Cuprous oxide (Cu2O) nanostructure has been synthesized using an electrochemical method with a two-electrode system. Cu foils were used as electrodes and NH2(OH) was utilized as the reducing agent. The effects of pH and applied voltages on the morphology of the product were investigated. The morphology and optical properties of Cu2O particles were characterized using scanning electron microscopy, x-ray diffraction, and diffuse reflectance spectra. The synthesized Cu2O nanostructures that formed in the vicinity of the anode at 2 V and pH = 11 showed high uniform distribution, small size, and good electrochemical sensing. These Cu2O nanoparticles were coated on an Indium tin oxide substrate and applied to detect non-enzyme glucose as excellent biosensors. The non-enzyme glucose biosensors exhibited good performance with high response, good selectivity, wide linear detection range, and a low detection limit at 0.4 μM. Synthesized Cu2O nanostructures are potential materials for a non-enzyme glucose biosensor.

Preparing cuprous oxide nanomaterials by electrochemical method for non-enzymatic glucose biosensor.

PubMed

Nguyen, Thu-Thuy; Huy, Bui The; Hwang, Seo-Young; Vuong, Nguyen Minh; Pham, Quoc-Thai; Nghia, Nguyen Ngoc; Kirtland, Aaron; Lee, Yong-Ill

2018-05-18

Cuprous oxide (Cu 2 O) nanostructure has been synthesized using an electrochemical method with a two-electrode system. Cu foils were used as electrodes and NH 2 (OH) was utilized as the reducing agent. The effects of pH and applied voltages on the morphology of the product were investigated. The morphology and optical properties of Cu 2 O particles were characterized using scanning electron microscopy, x-ray diffraction, and diffuse reflectance spectra. The synthesized Cu 2 O nanostructures that formed in the vicinity of the anode at 2 V and pH = 11 showed high uniform distribution, small size, and good electrochemical sensing. These Cu 2 O nanoparticles were coated on an Indium tin oxide substrate and applied to detect non-enzyme glucose as excellent biosensors. The non-enzyme glucose biosensors exhibited good performance with high response, good selectivity, wide linear detection range, and a low detection limit at 0.4 μM. Synthesized Cu 2 O nanostructures are potential materials for a non-enzyme glucose biosensor.

Lipoxygenase-modified Ru-bpy/graphene oxide: Electrochemical biosensor for on-farm monitoring of non-esterified fatty acid.

PubMed

Veerapandian, Murugan; Hunter, Robert; Neethirajan, Suresh

2016-04-15

Elevated concentrations of non-esterified fatty acids (NEFA) in biological fluids are recognized as critical biomarkers for early diagnosis of dairy cow metabolic diseases. Herein, a cost-effective, electrochemically active, and bio-friendly sensor element based on ruthenium bipyridyl complex-modified graphene oxide nanosheets ([Ru(bpy)3](2+)-GO) is proposed as a biosensor platform for NEFA detection. Electrochemical analysis demonstrates that the [Ru(bpy)3](2+)-GO electrodes exhibit superior and durable redox properties compared to the pristine carbon and GO electrodes. Target specificity is accomplished through immobilization of the enzyme, lipoxygenase, which catalyzes the production of redox active species from NEFA. Lipoxygenases retain their catalytic ability upon immobilization and exhibit changes to amperometric signals upon interaction with various concentrations of standard NEFA and serum samples. Our study demonstrates that the [Ru(bpy)3](2+)-GO electrode has the potential to serve as a biosensor platform for developing a field deployable, rapid, and user-friendly detection tool for on-farm monitoring of dairy cow metabolic diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

An electrochemical sulfite biosensor based on gold coated magnetic nanoparticles modified gold electrode.

PubMed

Rawal, Rachna; Chawla, Sheetal; Pundir, Chandra Shekhar

2012-01-15

A sulfite oxidase (SO(X)) (EC 1.8.3.1) purified from Syzygium cumini leaves was immobilized onto carboxylated gold coated magnetic nanoparticles (Fe(3)O(4)@GNPs) electrodeposited onto the surface of a gold (Au) electrode through N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC)-N-hydroxy succinimide (NHS) chemistry. An amperometric sulfite biosensor was fabricated using SO(X)/Fe(3)O(4)@GNPs/Au electrode as working electrode, Ag/AgCl as standard and Pt wire as auxiliary electrode. The working electrode was characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Cyclic Voltammetry (CV), Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS) before and after immobilization of SO(X). The biosensor showed optimum response within 2s when operated at 0.2V (vs. Ag/AgCl) in 0.1 M Tris-HCl buffer, pH 8.5 and at 35 °C. Linear range and detection limit were 0.50-1000 μM and 0.15 μM (S/N=3) respectively. Biosensor was evaluated with 96.46% recovery of added sulfite in red wine and 1.7% and 3.3% within and between batch coefficients of variation respectively. Biosensor measured sulfite level in red and white wines. There was good correlation (r=0.99) between red wines sulfite value by standard DTNB (5,5'-dithio-bis-(2-nitrobenzoic acid)) method and the present method. Enzyme electrode was used 300 times over a period of 4 months, when stored at 4 °C. Biosensor has advantages over earlier biosensors that it has excellent electrocatalysis towards sulfite, lower detection limit, higher storage stability and no interference by ascorbate, cysteine, fructose and ethanol. Copyright © 2011 Elsevier B.V. All rights reserved.

Enhancing biosensor properties of conducting polymers via copolymerization: Synthesis of EDOT-substituted bis(2-pyridylimino)isoindolato-palladium complex and electrochemical sensing of glucose by its copolymerized film.

PubMed

Tekbaşoğlu, Tuğçe Yazıcı; Soganci, Tugba; Ak, Metin; Koca, Atıf; Şener, M Kasım

2017-01-15

1,3-Bis(2-pyridylimino)isoindoline derivative bearing 3,4-ethylenedioxythiophene (EDOT-BPI) and its palladium complex (EDOT-PdBPI) were synthesized and characterized by FT-IR, 1 H NMR, 13 C NMR, UV-Vis spectroscopies and via mass spectrometric analysis. Polymerization of EDOT-PdBPI and copolymerization with 4-amino-N-(2,5-di(thiophene-2-yl)-1H-pyrrol-1-yl)benzamide (HKCN) were carried out by an electrochemical method. In addition, P(EDOT-PdBPI-co-HKCN) modified graphite rod electrode was improved for amperometric glucose sensor based on glucose oxidase (GOx). In this novel biosensor matrix, amino groups in HKCN were used for the enzyme immobilization. On the other hand, EDOT-PdBPI used to mediate the bioelectrocatalytic reaction. Amperometric detection was carried out following oxygen consumption at -0.7V vs. the Ag reference electrode in phosphate buffer (50mM, pH 6.0). The novel biosensor showed a linear amperometric response for glucose within a concentration range of 0.25mM to 2.5mM (LOD: 0.176mM). Amperometric signals at 1mM of glucose were 17.9μA under anaerobic conditions. Amperometric response of the P(EDOT-PdBPI-co-HKCN)/GOx electrode decreased only by 13% within eight weeks. The P(EDOT-PdBPI-co-HKCN)/GOx electrode showed good selectivity in the presence of ethanol and phenol. This result shows that, modification of the proposed biosensor by copolymerization of amine functionalized monomer, which is indispensable to the enzyme immobilization, with palladium complex bearing monomer, which is mediate the bioelectrocatalytic reaction, have provided to give perfect response to different glucose concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

Protein-Modified-Paramagnetic-Particles as a Tool for Detection of Silver(I) Ions

NASA Astrophysics Data System (ADS)

Kizek, R.; Krizkova, S.; Adam, V.; Huska, D.; Hubalek, J.; Trnkova, L.

2009-04-01

In a number of published articles the toxic effect of silver(I) ions on aquatic organisms is described. Silver(I) ions in aquatic environment are stable in a wide range of pH. Under alkali pH AgOH and Ag(OH)2- can be formed. However, in water environment there are many compounds to interact with silver(I) ions. The most important ones are chloride anions, which forms insoluble precipitate with silver(I) ions (AgCl). The insoluble silver containing compounds do not pose any threat to aquatic organisms. Toxicity of silver ions is probably caused by their very good affinity to nucleic acids and also proteins. The binding into active enzyme site leads to the expressive enzyme reaction inhibition. Silver(I) ions are into living environment introduced thanks to anthropogenic activities. They easily contaminate atmosphere as well as aquatic environment or soils. Several authors described using of carbon electrode as working electrode for determination of silver. Recently, we have suggested heavy metal biosensor based on interaction of metal ions with low molecular mass protein called metallothionein (MT), which was adsorbed on the surface of hanging mercury drop electrode (HMDE). The biosensor was successfully used for detection of cadmium(II) and zinc(II) ions, cisplatin, cisplatin-DNA adducts and palladium(II) ions. Due to the convincing results with MT as biological component we report on suggesting of heavy metal biosensor based on immobilization of metallothionein (MT) on the surface of carbon paste electrode (CPE) via MT-antibodies. Primarily we studied of basic electrochemical behaviour of MT at surface of carbon paste electrode by using of square wave voltammetry (SWV). Detection limit (3 S/N) for MT was evaluated as 0.1 μg/ml. After that we have evaluated the electroactivity of MT at surface of SWV, we aimed our attention on the way of capturing of MT on the surface of CPE. We choose antibody against MT obtained from chicken eggs for these purposes. Antibodies incorporated mixed with carbon paste were stable. Even after 14 days we did not determine change in the peak height higher than 5 %. Further linkage of MT with polyclonal chicken antibodies incorporated in carbon paste electrode was determined by SWV. Two signals were observed in voltammograms, cysMT corresponding to -SH moieties of MT and Wa corresponding to tryptophan residues of chicken antibodies. We optimized time of interaction (300 s) and concentration of MT (125 µg/ml) to suggest silver(I) ions biosensor. Biosensor (MT-antibody-modified CPE) prepared under the optimized conditions was utilized for silver(I) ions detection. The detection limit (3 S/N) for silver(I) ions were estimated as 100 nM. The proposed biosensor was tested by detection of silver(I) ions spiked in various water samples (from very pure distilled water to rainwater). Recoveries varied from 74 to 104 %. MT, low molecular mass proteins rich cysteine, play important role in the processes of heavy metals ions metabolism. Due to their unique physico-chemical properties they are able to bind heavy metals with high affinity. We used this feature to suggest simple biosensor based on immobilization of MT on the surface of carbon paste electrode via chicken antibodies against MT. The suggested biosensor was further successfully employed to detect silver(I) ions. The main advantage of the biosensor is that it can be easily miniaturized, whereas carbon nanostructures with immobilized MT should be used as working electrodes. Acknowledgements Financial support from INCHEMBIOL MSMT 0021622412 and GA CR 526/07/0674 is highly acknowledged.

An independently addressable microbiosensor array: what are the limits of sensing element density?

PubMed

Yu, P; Wilson, G S

2000-01-01

A microdisc sensor array, prepared by thin film technology, has been used as a model for miniaturized multi-functional biosensors. It consists of a series of wells, 20 microns in diameter, possessing a 1000 A Pt layer at the bottom that serves as the indicating electrode. The depth of the wells ranged from 2.3-24 microns, depending on the photoresist employed and the spinning speed used to coat the electrode interconnect grid. Ten such wells were arranged in a circular array within an area of radius 130 microns. The center to center distance between any two of the discs ranged from 30 to 155 microns. Each disc is connected by a conductive film line to corresponding pads on the side of the sensor chip. A cylinder placed on top of the chip array formed the electrochemical cell into which a common reference and counter electrode were placed. The reference electrode was operated at ground potential. Prior to the evaluation of enzyme sensors, an assessment of "chemical cross-talk", the perturbation of sensor response resulting from the overlap of proximal diffusion layers, was made using Fe(CN)6(4-). The preliminary conclusion is that the sensing elements probably must be separated by about 100 microns in order to avoid interference from adjacent sensors. A technique was developed for the precision delivery of enzyme and cross-linking agent to the 2.3 microns cavity, having a capacity of 4 pL. This procedure makes possible the preparation of sensor arrays capable of detecting different analytes by employing different enzymes. The sensors gave reasonably rapid (2-4 s) response with linearity (up to about 10 mM. However, the sensors in the center of the array clearly showed the effects of depletion of substrates by the surrounding sensors.

Amperometric inhibition biosensors based on horseradish peroxidase and gold sononanoparticles immobilized onto different electrodes for cyanide measurements.

PubMed

Attar, Aisha; Cubillana-Aguilera, Laura; Naranjo-Rodríguez, Ignacio; de Cisneros, José Luis Hidalgo-Hidalgo; Palacios-Santander, José María; Amine, Aziz

2015-02-01

New biosensors based on inhibition for the detection of cyanide and the comparison of the analytical performances of nine enzyme biosensor designs by using three different electrodes: Sonogel-Carbon, glassy carbon and gold electrodes were discussed. Three different horseradish peroxidase immobilization procedures with and without gold sononanoparticles were studied. The amperometric measurements were performed at an applied potential of -0.15V vs. Ag/AgCl in 50mM sodium acetate buffer solution pH=5.0. The apparent kinetic parameters (Kmapp, Vmaxapp) of immobilized HRP were calculated in the absence of inhibitor (cyanide) by using caffeic acid, hydroquinone, and catechol as substrates. The presence of gold sononanoparticles enhanced the electron transfer reaction and improved the analytical performance of the biosensors. The HRP kinetic interactions reveal non-competitive binding of cyanide with an apparent inhibition constant (Ki) of 2.7μM and I50 of 1.3μM. The determination of cyanide can be achieved in a dynamic range of 0.1-58.6μM with a detection limit of 0.03μM which is lower than those reported by previous studies. Hence this biosensing methodology can be used as a new promising approach for detecting cyanide. Copyright © 2014. Published by Elsevier B.V.

A microfabricated low cost enzyme-free glucose fuel cell for powering low-power implantable devices

NASA Astrophysics Data System (ADS)

Oncescu, Vlad; Erickson, David

In the past decade the scientific community has showed considerable interest in the development of implantable medical devices such as muscle stimulators, neuroprosthetic devices, and biosensors. Those devices have low power requirements and can potentially be operated through fuel cells using reactants present in the body such as glucose and oxygen instead of non-rechargeable lithium batteries. In this paper, we present a thin, enzyme-free fuel cell with high current density and good stability at a current density of 10 μA cm -2. A non-enzymatic approach is preferred because of higher long term stability. The fuel cell uses a stacked electrode design in order to achieve glucose and oxygen separation. An important characteristic of the fuel cell is that it has no membrane separating the electrodes, which results in low ohmic losses and small fuel cell volume. In addition, it uses a porous carbon paper support for the anodic catalyst layer which reduces the amount of platinum or other noble metal catalysts required for fabricating high surface area electrodes with good reactivity. The peak power output of the fuel cell is approximately 2 μW cm -2 and has a sustainable power density of 1.5 μW cm -2 at 10 μA cm -2. An analysis on the effects of electrode thickness and inter electrode gap on the maximum power output of the fuel cell is also performed.

Manganese porphyrin decorated on DNA networks as quencher and mimicking enzyme for construction of ultrasensitive photoelectrochemistry aptasensor.

PubMed

Huang, Liaojing; Zhang, Li; Yang, Liu; Yuan, Ruo; Yuan, Yali

2018-05-01

In this work, the manganese porphyrin (MnPP) decorated on DNA networks could serve as quencher and mimicking enzyme to efficiently reduce the photocurrent of photoactive material 3,4,9,10-perylene tetracarboxylic acid (PTCA), which was elaborately used to construct a novel label-free aptasensor for ultrasensitive detection of thrombin (TB) in a signal-off manner. The Au-doped PTCA (PTCA-PEI-Au) with outstanding membrane-forming and photoelectric property was modified on electrode to acquire a strong initial photoelectrochemistry (PEC) signal. Afterward, target binding aptamer Ι (TBAΙ) was modified on electrode to specially recognize target TB, which could further combine with TBAII and single-stranded DNA P1-modified platinum nanoparticles (TBAII-PtNPs-P1) for immobilizing DNA networks with abundant MnPP. Ingeniously, the MnPP could not only directly quench the photocurrent of PTCA, but also acted as hydrogen peroxide (HRP) mimicking enzyme to remarkably stimulate the deposition of benzo-4-chlorhexidine (4-CD) on electrode for further decreasing the photocurrent of PTCA, thereby obtaining a definitely low photocurrent for detection of TB. As a result, the proposed PEC aptasensor illustrated excellent sensitivity with a low detection limit down to 3 fM, exploiting a new avenue about intergrating two functions in one substance for ultrasensitive biological monitoring. Copyright © 2017 Elsevier B.V. All rights reserved.

A sensitive glucose biosensor based on Ag@C core-shell matrix.

PubMed

Zhou, Xuan; Dai, Xingxin; Li, Jianguo; Long, Yumei; Li, Weifeng; Tu, Yifeng

2015-04-01

Nano-Ag particles were coated with colloidal carbon (Ag@C) to improve its biocompatibility and chemical stability for the preparation of biosensor. The core-shell structure was evidenced by transmission electron microscope (TEM) and the Fourier transfer infrared (FTIR) spectra revealed that the carbon shell is rich of function groups such as -OH and -COOH. The as-prepared Ag@C core-shell structure can offer favorable microenvironment for immobilizing glucose oxidase and the direct electrochemistry process of glucose oxidase (GOD) at Ag@C modified glassy carbon electrode (GCE) was realized. The modified electrode exhibited good response to glucose. Under optimum experimental conditions the biosensor linearly responded to glucose concentration in the range of 0.05-2.5mM, with a detection limit of 0.02mM (S/N=3). The apparent Michaelis-Menten constant (KM(app)) of the biosensor is calculated to be 1.7mM, suggesting high enzymatic activity and affinity toward glucose. In addition, the GOD-Ag@C/Nafion/GCE shows good reproducibility and long-term stability. These results suggested that core-shell structured Ag@C is an ideal matrix for the immobilization of the redox enzymes and further the construction of the sensitive enzyme biosensor. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiplexed enzyme-free electrochemical immunosensor based on ZnO nanorods modified reduced graphene oxide-paper electrode and silver deposition-induced signal amplification strategy.

PubMed

Sun, Guoqiang; Zhang, Lina; Zhang, Yan; Yang, Hongmei; Ma, Chao; Ge, Shenguang; Yan, Mei; Yu, Jinghua; Song, Xianrang

2015-09-15

Herein, an origami multiplexed enzyme-free electrochemical (EC) immunodevice is developed for the first time. Typically, ZnO nanorods (ZNRs) modified reduced graphene oxide (rGO)-paper electrode is used as a sensor platform, in which rGO improves the electronic transmission rate and ZNRs provide abundant sites for capture probes binding. Furthermore, by combining the large surface area of rGO and high catalytic activity of bovine serum protein (BSA)-stabilized silver nanoparticles (Ag@BSA) toward H2O2 reduction, rGO/Ag@BSA composites can be used as an excellent signal labels. The current signal is generated from the reduction of H2O2 and further amplified by a subsequent signal labels-promoted deposition of silver. Under optimal conditions, the proposed immunoassays exhibit excellent precision, high sensitivity and a wide linear range of 0.002-120 mIU mL(-1) for human chorionic gonadotropin, 0.001-110 ng mL(-1) for prostate-specific antigen, and 0.001-100 ng mL(-1) for carcinoembryonic antigen. The results for real sample analysis demonstrate that the newly constructed immunosensor arrays provide a simple and cost-effective method for clinical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hosein, W. K.; Yorita, A. M.; Tolosa, V. M.

The enzyme immobilization process, one step in creating an enzymatic biosensor, was characterized and analyzed as a function of its physical properties. The neural glutamic biosensor is a flexible device, effectively minimizing trauma to the area of implantation. The Multielectrode Array (MEA) is composed primarily of a proprietary polymer which has been successfully implanted into human subjects in recent years. This polymer allows the device the pliability that other devices normally lack, though this poses some challenges to implantation. The electrodes are made of Platinum (Pt), and can range in number from eight to thirty two electrodes per device. Thesemore » electrodes are electroplated with a semipermeable polymer layer to improve selectivity of the electrode to the neurotransmitter of interest, in this case glutamate. A signal is created from the interaction of glutamate in the brain with the glutamate oxidase (GluOx) which is immobilized on the surface of the electrode by using crosslinking chemistry in conjunction with glutaraldehyde and Bovine Serum Albumin (BSA). The glutamate is oxidized by glutamate oxidase, producing α-ketoglutarate and hydrogen peroxide (H 2O 2) as a by-product. The production of H 2O 2 is crucial for detection of the presence of the glutamate within the enzymatic coating, as it diffuses through the enzyme layer and oxidizes at the surface of the electrode. This oxidation is detectable by measurable change in the current using amperometry. Hence, the MEA allows for in vivo monitoring of neurotransmitter activity in real time. The sensitivity of the sensor to these neurotransmitters is dependent on the thickness of the layer, which is investigated in these experiments in order to optimize the efficacy of the device to detecting the substrate, once implanted.« less

Assessment of Chronological Effects of Irreversible Electroporation on Hilar Bile Ducts in a Porcine Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Jae Woong, E-mail: cooljay@korea.ac.kr; Lu, David S. K., E-mail: dlu@mednet.ucla.edu; Osuagwu, Ferdnand, E-mail: fosuagwu@mednet.ucla.edu

2013-11-07

PurposeTo evaluate the chronological effects of irreversible electroporation (IRE) on large hilar bile ducts in an in vivo porcine model correlated with computed tomography (CT) cholangiography and histopathology.Materials and MethodsTwelve IRE zones were made along hilar bile ducts intraoperatively under ultrasound (US)-guidance in 11 pigs. Paired electrodes were placed either on opposing sides of the bile duct (straddle [STR]) or both on one side of the bile duct (one-sided [OSD]). The shortest electrode-to-duct distance was classified as periductal (≤2 mm) or nonperiductal (>2 mm). CT cholangiography and laboratory tests were performed before IRE and again at 2 days, 4 weeks, and 8 weeks after IRE.more » Degree of bile duct injury were graded as follows: grade 0 = no narrowing; grade 1 = ≤50 % duct narrowing; grade 2 = >50 % narrowing without proximal duct dilatation; grade 3 = grade 2 with proximal duct dilatation; and grade 4 = grade 3 with enzyme elevation. Pigs were selected for killing and histopathology at 2 days, 4, and 8 weeks.ResultsNonperiductal electrode placement produced no long-term strictures in 5 of 5 ducts. Periductal electrode placement produced mild narrowing in 6 of 7 ducts: 5 grade 1 and 1 grade 2. None showed increased enzymes. There was no significant difference between STR versus OSD electrode placement. Histopathology showed minor but relatively greater ductal mural changes in narrowed ducts.ConclusionIn the larger hilar ducts, long-term patency and mural integrity appear resistant to IRE damage with the energy deposition used, especially if the electrode is not immediately periductal in position.« less

Indirect Determination of Mercury Ion by Inhibition of a Glucose Biosensor Based on ZnO Nanorods

PubMed Central

Chey, Chan Oeurn; Ibupoto, Zafar Hussain; Khun, Kimleang; Nur, Omer; Willander, Magnus

2012-01-01

A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10−6 mM to 0.5 × 10−4 mM, and from 0.5 × 10−4 mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10−3 mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users. PMID:23202200

Indirect determination of mercury ion by inhibition of a glucose biosensor based on ZnO nanorods.

PubMed

Chey, Chan Oeurn; Ibupoto, Zafar Hussain; Khun, Kimleang; Nur, Omer; Willander, Magnus

2012-11-06

A potentiometric glucose biosensor based on immobilization of glucose oxidase (GOD) on ZnO nanorods (ZnO-NRs) has been developed for the indirect determination of environmental mercury ions. The ZnO-NRs were grown on a gold coated glass substrate by using the low temperature aqueous chemical growth (ACG) approach. Glucose oxidase in conjunction with a chitosan membrane and a glutaraldehyde (GA) were immobilized on the surface of the ZnO-NRs using a simple physical adsorption method and then used as a potentiometric working electrode. The potential response of the biosensor between the working electrode and an Ag/AgCl reference electrode was measured in a 1mM phosphate buffer solution (PBS). The detection limit of the mercury ion sensor was found to be 0.5 nM. The experimental results provide two linear ranges of the inhibition from 0.5 × 10(-6) mM to 0.5 × 10(-4) mM, and from 0.5 × 10(-4) mM to 20 mM of mercury ion for fixed 1 mM of glucose concentration in the solution. The linear range of the inhibition from 10(-3) mM to 6 mM of mercury ion was also acquired for a fixed 10 mM of glucose concentration. The working electrode can be reactivated by more than 70% after inhibition by simply dipping the used electrode in a 10 mM PBS solution for 7 min. The electrodes retained their original enzyme activity by about 90% for more than three weeks. The response to mercury ions was highly sensitive, selective, stable, reproducible, and interference resistant, and exhibits a fast response time. The developed glucose biosensor has a great potential for detection of mercury with several advantages such as being inexpensive, requiring minimum hardware and being suitable for unskilled users.

Alpha-Glucosidase Enzyme Biosensor for the Electrochemical Measurement of Antidiabetic Potential of Medicinal Plants

NASA Astrophysics Data System (ADS)

Mohiuddin, M.; Arbain, D.; Islam, A. K. M. Shafiqul; Ahmad, M. S.; Ahmad, M. N.

2016-02-01

A biosensor for measuring the antidiabetic potential of medicinal plants was developed by covalent immobilization of α-glucosidase (AG) enzyme onto amine-functionalized multi-walled carbon nanotubes (MWCNTs-NH2). The immobilized enzyme was entrapped in freeze-thawed polyvinyl alcohol (PVA) together with p-nitrophenyl-α- d-glucopyranoside (PNPG) on the screen-printed carbon electrode at low pH to prevent the premature reaction between PNPG and AG enzyme. The enzymatic reaction within the biosensor is inhibited by bioactive compounds in the medicinal plant extracts. The capability of medicinal plants to inhibit the AG enzyme on the electrode correlates to the potential of the medicinal plants to inhibit the production of glucose from the carbohydrate in the human body. Thus, the inhibition indicates the antidiabetic potential of the medicinal plants. The performance of the biosensor was evaluated to measure the antidiabetic potential of three medicinal plants such as Tebengau ( Ehretis laevis), Cemumar ( Micromelum pubescens), and Kedondong ( Spondias dulcis) and acarbose (commercial antidiabetic drug) via cyclic voltammetry, amperometry, and spectrophotometry. The cyclic voltammetry (CV) response for the inhibition of the AG enzyme activity by Tebengau plant extracts showed a linear relation in the range from 0.423-8.29 μA, and the inhibition detection limit was 0.253 μA. The biosensor exhibited good sensitivity (0.422 μA/mg Tebengau plant extracts) and rapid response (22 s). The biosensor retains approximately 82.16 % of its initial activity even after 30 days of storage at 4 °C.

Wired enzyme electrodes--a retroperspective story about an exciting time at University of Texas at Austin and its impact on my scientific career.

PubMed

Lindquist, Sten-Eric

2013-07-22

The present paper features an exciting time in the late 1980s when I, as a visiting scientist, had the privilege to participate in the early and very exciting development of the in vivo redox-polymer-wired glucose sensor in Professor Adam Heller's laboratory at the Department of Chemical Engineering at University of Texas at Austin. This story is followed by an overview of the research my visit initiated at Uppsala University. In collaboration with Swedish colleagues, we explored a few of the many possibilities to form new biosensors by utilizing Prof. Heller's concept of cross-linked redox-polymer/redox-enzyme electrodes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modified Electrodes Used for Electrochemical Detection of Metal Ions in Environmental Analysis

PubMed Central

March, Gregory; Nguyen, Tuan Dung; Piro, Benoit

2015-01-01

Heavy metal pollution is one of the most serious environmental problems, and regulations are becoming stricter. Many efforts have been made to develop sensors for monitoring heavy metals in the environment. This review aims at presenting the different label-free strategies used to develop electrochemical sensors for the detection of heavy metals such as lead, cadmium, mercury, arsenic etc. The first part of this review will be dedicated to stripping voltammetry techniques, on unmodified electrodes (mercury, bismuth or noble metals in the bulk form), or electrodes modified at their surface by nanoparticles, nanostructures (CNT, graphene) or other innovative materials such as boron-doped diamond. The second part will be dedicated to chemically modified electrodes especially those with conducting polymers. The last part of this review will focus on bio-modified electrodes. Special attention will be paid to strategies using biomolecules (DNA, peptide or proteins), enzymes or whole cells. PMID:25938789

Direct mapping of local redox current density on a monolith electrode by laser scanning.

PubMed

Lee, Seung-Woo; Lopez, Jeffrey; Saraf, Ravi F

2013-09-15

An optical method of mapping local redox reaction over a monolith electrode using simple laser scanning is described. As the optical signal is linearly proportional to the maximum redox current that is measured concomitantly by voltammetry, the optical signal quantitatively maps the local redox current density distribution. The method is demonstrated on two types of reactions: (1) a reversible reaction where the redox moieties are ionic, and (2) an irreversible reaction on two different types of enzymes immobilized on the electrode where the reaction moieties are nonionic. To demonstrate the scanning capability, the local redox behavior on a "V-shaped" electrode is studied where the local length scale and, hence, the local current density, is nonuniform. The ability to measure the current density distribution by this method will pave the way for multianalyte analysis on a monolith electrode using a standard three-electrode configuration. The method is called Scanning Electrometer for Electrical Double-layer (SEED). Copyright © 2013 Elsevier B.V. All rights reserved.

Amperometric Enzyme-Based Biosensors for Application in Food and Beverage Industry

NASA Astrophysics Data System (ADS)

Csöoregi, Elisabeth; Gáspñr, Szilveszter; Niculescu, Mihaela; Mattiasson, Bo; Schuhmann, Wolfgang

Continuous, sensitive, selective, and reliable monitoring of a large variety of different compounds in various food and beverage samples is of increasing importance to assure a high-quality and tracing of any possible source of contamination of food and beverages. Most of the presently used classical analytical methods are often requiring expensive instrumentation, long analysis times and well-trained staff. Amperometric enzyme-based biosensors on the other hand have emerged in the last decade from basic science to useful tools with very promising application possibilities in food and beverage industry. Amperometric biosensors are in general highly selective, sensitive, relatively cheap, and easy to integrate into continuous analysis systems. A successful application of such sensors for industrial purposes, however, requires a sensor design, which satisfies the specific needs of monitoring the targeted analyte in the particular application, Since each individual application needs different operational conditions and sensor characteristics, it is obvious that biosensors have to be tailored for the particular case. The characteristics of the biosensors are depending on the used biorecognition element (enzyme), nature of signal transducer (electrode material) and the communication between these two elements (electron-transfer pathway).

A New Laccase Based Biosensor for Tartrazine.

PubMed

Mazlan, Siti Zulaikha; Lee, Yook Heng; Hanifah, Sharina Abu

2017-12-09

Laccase enzyme, a commonly used enzyme for the construction of biosensors for phenolic compounds was used for the first time to develop a new biosensor for the determination of the azo-dye tartrazine. The electrochemical biosensor was based on the immobilization of laccase on functionalized methacrylate-acrylate microspheres. The biosensor membrane is a composite of the laccase conjugated microspheres and gold nanoparticles (AuNPs) coated on a carbon-paste screen-printed electrode. The reaction involving tartrazine can be catalyzed by laccase enzyme, where the current change was measured by differential pulse voltammetry (DPV) at 1.1 V. The anodic peak current was linear within the tartrazine concentration range of 0.2 to 14 μM ( R ² = 0.979) and the detection limit was 0.04 μM. Common food ingredients or additives such as glucose, sucrose, ascorbic acid, phenol and sunset yellow did not interfere with the biosensor response. Furthermore, the biosensor response was stable up to 30 days of storage period at 4 °C. Foods and beverage were used as real samples for the biosensor validation. The biosensor response to tartrazine showed no significant difference with a standard HPLC method for tartrazine analysis.

A New Laccase Based Biosensor for Tartrazine

PubMed Central

Mazlan, Siti Zulaikha; Lee, Yook Heng; Hanifah, Sharina Abu

2017-01-01

Laccase enzyme, a commonly used enzyme for the construction of biosensors for phenolic compounds was used for the first time to develop a new biosensor for the determination of the azo-dye tartrazine. The electrochemical biosensor was based on the immobilization of laccase on functionalized methacrylate-acrylate microspheres. The biosensor membrane is a composite of the laccase conjugated microspheres and gold nanoparticles (AuNPs) coated on a carbon-paste screen-printed electrode. The reaction involving tartrazine can be catalyzed by laccase enzyme, where the current change was measured by differential pulse voltammetry (DPV) at 1.1 V. The anodic peak current was linear within the tartrazine concentration range of 0.2 to 14 μM (R2 = 0.979) and the detection limit was 0.04 μM. Common food ingredients or additives such as glucose, sucrose, ascorbic acid, phenol and sunset yellow did not interfere with the biosensor response. Furthermore, the biosensor response was stable up to 30 days of storage period at 4 °C. Foods and beverage were used as real samples for the biosensor validation. The biosensor response to tartrazine showed no significant difference with a standard HPLC method for tartrazine analysis. PMID:29232842

CYP450 2B4 covalently attached to carbon and gold screen printed electrodes by diazonium salt and thiols monolayers.

PubMed

Alonso-Lomillo, M A; Yardimci, C; Domínguez-Renedo, O; Arcos-Martínez, M J

2009-02-02

An easy covalent immobilization method used to develop enzyme biosensors based on carbon and gold screen printed electrodes (SPCEs and gold SPEs) is described. The linkage of biomolecules through 4-nitrobenzenediazonium tetrafluoroborate, mercaptopropionic acid and thioctic acid monolayers has been attempted using bare SPCEs and gold SPEs, as well as gold nanoparticles (AuNPs) modified SPCEs and gold SPEs. Direct covalent attachment of Cytochrome P450 2B4 (CYP450 2B4) to the transducer has been carried out by carbodiimide and hydroxysuccinimide. Experimental variables in the immobilization process and in the chronoamperometric determination of Phenobarbital (PB) have been optimized by the experimental design methodology. Reproducibility of the different biosensors has been checked under the optimum conditions, yielding values lower than 6%. Their performances have been shown by the determination of PB in pharmaceutical drugs.

Utilization of highly purified single wall carbon nanotubes dispersed in polymer thin films for an improved performance of an electrochemical glucose sensor.

PubMed

Goornavar, Virupaxi; Jeffers, Robert; Biradar, Santoshkumar; Ramesh, Govindarajan T

2014-07-01

In this work we report the improved performance an electrochemical glucose sensor based on a glassy carbon electrode (GCE) that has been modified with highly purified single wall carbon nanotubes (SWCNTs) dispersed in polyethyleneimine (PEI), polyethylene glycol (PEG) and polypyrrole (PPy). The single wall carbon nanotubes were purified by both thermal and chemical oxidation to achieve maximum purity of ~98% with no damage to the tubes. The SWCNTs were then dispersed by sonication in three different organic polymers (1.0mg/ml SWCNT in 1.0mg/ml of organic polymer). The stable suspension was coated onto the GCE and electrochemical characterization was performed by Cyclic Voltammetry (CV) and Amperometry. The electroactive enzyme glucose oxidase (GOx) was immobilized on the surface of the GCE/(organic polymer-SWCNT) electrode. The amperometric detection of glucose was carried out at 0.7 V versus Ag/AgCl. The GCE/(SWCNT-PEI, PEG, PPY) gave a detection limit of 0.2,633 μM, 0.434 μM, and 0.9,617 μM, and sensitivities of 0.2411 ± 0.0033 μA mM(-1), r(2)=0.9984, 0.08164 ± 0.001129 μA mM(-1), r(2)=0.9975, 0.04189 ± 0.00087 μA mM(-1), and r(2)=0.9944 respectively and a response time of less than 5s. The use of purified SWCNTs has several advantages, including fast electron transfer rate and stability in the immobilized enzyme. The significant enhancement of the SWCNT modified electrode as a glucose sensor can be attributed to the superior conductivity and large surface area of the well dispersed purified SWCNTs. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrochemical Detection of Multiple Bioprocess Analytes

NASA Technical Reports Server (NTRS)

Rauh, R. David

2010-01-01

An apparatus that includes highly miniaturized thin-film electrochemical sensor array has been demonstrated as a prototype of instruments for simultaneous detection of multiple substances of interest (analytes) and measurement of acidity or alkalinity in bioprocess streams. Measurements of pH and of concentrations of nutrients and wastes in cell-culture media, made by use of these instruments, are to be used as feedback for optimizing the growth of cells or the production of desired substances by the cultured cells. The apparatus is designed to utilize samples of minimal volume so as to minimize any perturbation of monitored processes. The apparatus can function in a potentiometric mode (for measuring pH), an amperometric mode (detecting analytes via oxidation/reduction reactions), or both. The sensor array is planar and includes multiple thin-film microelectrodes covered with hydrous iridium oxide. The oxide layer on each electrode serves as both a protective and electrochemical transducing layer. In its transducing role, the oxide provides electrical conductivity for amperometric measurement or pH response for potentiometric measurement. The oxide on an electrode can also serve as a matrix for one or more enzymes that render the electrode sensitive to a specific analyte. In addition to transducing electrodes, the array includes electrodes for potential control. The array can be fabricated by techniques familiar to the microelectronics industry. The sensor array is housed in a thin-film liquid-flow cell that has a total volume of about 100 mL. The flow cell is connected to a computer-controlled subsystem that periodically draws samples from the bioprocess stream to be monitored. Before entering the cell, each 100-mL sample is subjected to tangential-flow filtration to remove particles. In the present version of the apparatus, the electrodes are operated under control by a potentiostat and are used to simultaneously measure the pH and the concentration of glucose. It is anticipated that development of procedures for trapping more enzymes into hydrous iridium oxide (and possibly into other electroactive metal oxides) and of means for imparting long-term stability to the transducer layers should make it possible to monitor concentrations of products of many enzyme reactions for example, such key bioprocess analytes as amino acids, vitamins, lactose, and acetate.

Engineering a biospecific communication pathway between cells and electrodes

NASA Astrophysics Data System (ADS)

Collier, Joel H.; Mrksich, Milan

2006-02-01

Methods for transducing the cellular activities of mammalian cells into measurable electronic signals are important in many biotechnical applications, including biosensors, cell arrays, and other cell-based devices. This manuscript describes an approach for functionally integrating cellular activities and electrical processes in an underlying substrate. The cells are engineered with a cell-surface chimeric receptor that presents the nonmammalian enzyme cutinase. Action of this cell-surface cutinase on enzyme substrate self-assembled monolayers switches a nonelectroactive hydroxyphenyl ester to an electroactive hydroquinone, providing an electrical activity that can be identified with cyclic voltammetry. In this way, cell-surface enzymatic activity is transduced into electronic signals. The development of strategies to directly interface the activities of cells with materials will be important to enabling a broad class of hybrid microsystems that combine living and nonliving components. biomaterial | extracellular matrix | signal transduction

Modified insulator semiconductor electrode with functionalized nanoparticles for Proteus mirabilis bacteria biosensor development.

PubMed

Braham, Yosra; Barhoumi, Houcine; Maaref, Abderrazak; Bakhrouf, Amina; Jaffrezic-Renault, Nicole

2013-12-01

The development of enzymatic sensors for biological purposes such as biomedicine, pharmacy, food industry, and environmental toxicity requires the purification step of the enzyme. To prevent the loss of the enzyme activity, a new strategy is held in order to immobilize the bacteria. It will constitute the biological sensing element leading to a high operational stability and multiple adaptations to various conditions such as temperature, pH and ionic strength changes. In this work we describe the development of a urea biosensor by immobilizing Proteus mirabilis bacteria onto an insulator-semiconductor electrode on functionalized Fe3O4 nanoparticles (NPs), using cationic, Poly (allylamine hydrochloride) then anionic, Poly (sodium 4-styrenesulfonate) polyelectrolytes, BSA (serum bovin albumin), and glutaraldehyde as a cross-linking agent. The response of P. mirabilis to urea addition is evaluated in homogeneous and heterogeneous phases. Before the immobilization step, the activity of urease produced from the P. mirabilis bacteria was attempted using the ion ammonium selective electrodes (ISEs). Adhesion of the bacteria cells on IS electrodes have been studied using contact angle measurements. After immobilization of the bacteria, on the (Si/SiO2/Si3N4) and (Si/SiO2) substrates, the relationship between the evolution of the flat band potential ∆VFB and the urea concentration is found to be linear for values ranging from 10(-2)M to 10(-5)M. © 2013.

Microbial surface displayed enzymes based biofuel cell utilizing degradation products of lignocellulosic biomass for direct electrical energy.

PubMed

Fan, Shuqin; Hou, Chuantao; Liang, Bo; Feng, Ruirui; Liu, Aihua

2015-09-01

In this work, a bacterial surface displaying enzyme based two-compartment biofuel cell for the direct electrical energy conversion from degradation products of lignocellulosic biomass is reported. Considering that the main degradation products of the lignocellulose are glucose and xylose, xylose dehydrogenase (XDH) displayed bacteria (XDH-bacteria) and glucose dehydrogenase (GDH) displayed bacteria (GDH-bacteria) were used as anode catalysts in anode chamber with methylene blue as electron transfer mediator. While the cathode chamber was constructed with laccase/multi-walled-carbon nanotube/glassy-carbon-electrode. XDH-bacteria exhibited 1.75 times higher catalytic efficiency than GDH-bacteria. This assembled enzymatic fuel cell exhibited a high open-circuit potential of 0.80 V, acceptable stability and energy conversion efficiency. Moreover, the maximum power density of the cell could reach 53 μW cm(-2) when fueled with degradation products of corn stalk. Thus, this finding holds great potential to directly convert degradation products of biomass into electrical energy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structural studies of enzyme-based microfluidic biofuel cells

NASA Astrophysics Data System (ADS)

Togo, Makoto; Takamura, Akimasa; Asai, Tatsuya; Kaji, Hirokazu; Nishizawa, Matsuhiko

An enzyme-based glucose/O 2 biofuel cell was constructed within a microfluidic channel to study the influence of electrode configuration and fluidic channel height on cell performance. The cell was composed of a bilirubin oxidase (BOD)-adsorbed O 2 cathode and a glucose anode prepared by co-immobilization of glucose dehydrogenase (GDH), diaphorase (Dp) and VK 3-pendant poly- L-lysine. The consumption of O 2 at the upstream cathode protected the downstream anode from interfering O 2 molecules, and consequently improved the cell performance (maximum cell current) ca. 10% for the present cell. The cell performance was also affected by the channel height. The output current and power of a 0.1 mm-height cell was significantly less than those of a 1 mm-height cell because of the depletion of O 2, as determined by the shape of the E- I curve at the cathode. On the other hand, the volume density of current and power was several times higher for the narrower cell.

Sensitive electrochemical aptamer cytosensor for highly specific detection of cancer cells based on the hybrid nanoelectrocatalysts and enzyme for signal amplification.

PubMed

Sun, Duanping; Lu, Jing; Zhong, Yuwen; Yu, Yanyan; Wang, Yu; Zhang, Beibei; Chen, Zuanguang

2016-01-15

Human cancer is becoming a leading cause of death in the world and the development of a straightforward strategy for early detection of cancer is urgently required. Herein, a sandwich-type electrochemical aptamer cytosensor was developed for detection of human liver hepatocellular carcinoma cells (HepG2) based on the hybrid nanoelectrocatalysts and enzyme for signal amplification. The thiolated TLS11a aptamers were used as a selective bio-recognition element, attached to the gold nanoparticles (AuNPs) modified the glassy carbon electrode (GCE) surface. Meanwhile, the electrochemical nanoprobes were fabricated through the G-quadruplex/hemin/aptamer complexes and horseradish peroxidase (HRP) immobilized on the surfaces of Au@Pd core-shell nanoparticle-modified magnetic Fe3O4/MnO2 beads (Fe3O4/MnO2/Au@Pd). After the target cells were captured, the hybrid nanoprobes were further assembled to form an aptamer-cell-nanoprobes sandwich-like system on the electrode surface. Then, hybrid Fe3O4/MnO2/Au@Pd nanoelectrocatalysts, G-quadruplex/hemin HRP-mimicking DNAzymes and the natural HRP enzyme efficiently catalyzed the oxidation of hydroquinone (HQ) with H2O2, amplifying the electrochemical signals and improving the detection sensitivity. This electrochemical cytosensor delivered a wide detection range of 1×10(2)-1×10(7)cellsmL(-1), high sensitivity with a low detection limit of 15cellsmL(-1), good selectivity and repeatability. Finally, an electrochemical reductive desorption method was performed to break gold-thiol bond and desorb the components on the AuNPs/GCE for regenerating the cytosensor. These results have demonstrated that the electrochemical cytosensor has the potential to be a feasible tool for cost-effective cancer cell detection in early cancer diagnosis. Copyright © 2015 Elsevier B.V. All rights reserved.

Stabilized Laccases as Heterogeneous Bioelectrocatalysts (Postprint)

DTIC Science & Technology

2012-10-01

nature, with examples that range from bacterial species to fungi and plants.19·101 However, certain properties of laccases, such as their protein...identified, includ- ing examples of extremophilic enzymes,l11·121 but the extracellu- lar laccases from wood-rotting fungi , such as Trametes spp...biomolecules not only affects the stability and selectivity of an enzyme towards different substrates but also the charge trans- fer at the electrode

Alpha-Glucosidase Enzyme Biosensor for the Electrochemical Measurement of Antidiabetic Potential of Medicinal Plants.

PubMed

Mohiuddin, M; Arbain, D; Islam, A K M Shafiqul; Ahmad, M S; Ahmad, M N

2016-12-01

A biosensor for measuring the antidiabetic potential of medicinal plants was developed by covalent immobilization of α-glucosidase (AG) enzyme onto amine-functionalized multi-walled carbon nanotubes (MWCNTs-NH2). The immobilized enzyme was entrapped in freeze-thawed polyvinyl alcohol (PVA) together with p-nitrophenyl-α-D-glucopyranoside (PNPG) on the screen-printed carbon electrode at low pH to prevent the premature reaction between PNPG and AG enzyme. The enzymatic reaction within the biosensor is inhibited by bioactive compounds in the medicinal plant extracts. The capability of medicinal plants to inhibit the AG enzyme on the electrode correlates to the potential of the medicinal plants to inhibit the production of glucose from the carbohydrate in the human body. Thus, the inhibition indicates the antidiabetic potential of the medicinal plants. The performance of the biosensor was evaluated to measure the antidiabetic potential of three medicinal plants such as Tebengau (Ehretis laevis), Cemumar (Micromelum pubescens), and Kedondong (Spondias dulcis) and acarbose (commercial antidiabetic drug) via cyclic voltammetry, amperometry, and spectrophotometry. The cyclic voltammetry (CV) response for the inhibition of the AG enzyme activity by Tebengau plant extracts showed a linear relation in the range from 0.423-8.29 μA, and the inhibition detection limit was 0.253 μA. The biosensor exhibited good sensitivity (0.422 μA/mg Tebengau plant extracts) and rapid response (22 s). The biosensor retains approximately 82.16 % of its initial activity even after 30 days of storage at 4 °C.

An amperometric urea bisosensor based on covalent immobilization of urease on N2 incorporated diamond nanowire electrode.

PubMed

Shalini, Jayakumar; Sankaran, Kamatchi Jothiramalingam; Lee, Chi-Young; Tai, Nyan-Hwa; Lin, I-Nan

2014-06-15

N2 incorporated diamond nanowire (N-DNW) film electrochemical biosensor has utilized for the quantitative determination of urea in aqueous solution and urine sample. N-DNW electrode is wet-chemically cleaned (oxidation) by boiling in a mixture of H2SO4 and HNO3 (3:1) at 200°C for 2h to remove graphite. Urease (Urs) and glutamate dehydrogenase (GLDH) are covalently attached to the oxidized N-DNW electrode by activating the COOH group of N-DNW using ethyl(dimethylaminopropyl)carbodiimide as the coupling agent and N-hydroxysuccinimide as activator. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy data reveal that carboxylic and hydroxyl functionalized nature of N-DNW electrodes Urs-GLDH immobilized N-DNW (Urs-GLDH/N-DNW) has been successfully utilized in urea biosensor which exhibits good performance in sensitivity (6.18 μA/mg dL/cm(2)), stability (~1 month), reproducibility, lower detection limit (3.87 mg/dL) and fast response time (>10s). Urs-GLDH/N-DNW also exhibits electrochemical response when tested for different concentration of human urine in buffer solution (from 1:9 to 4:6). In addition, Urs-GLDH/N-DNW bioelectrode retains 80% of its initial enzyme activity for <1 month, when stored at 4-6°C in a refrigerator. Copyright © 2013 Elsevier B.V. All rights reserved.

Electrochemical enzymatic fenitrothion sensor based on a tyrosinase/poly(2-hydroxybenzamide)-modified graphite electrode.

PubMed

Alves, Maria de Fátima; Corrêa, Ricardo Augusto Moreira de Souza; da Cruz, Filipe Soares; Franco, Diego Leoni; Ferreira, Lucas Franco

2018-07-15

This paper reports the electrosynthesis and characterisation of a polymeric film derived from 2-hydroxybenzamide over a graphite electrode and its application as an enzymatic biosensor for the determination and quantification of the pesticide fenitrothion. The material was analysed by scanning electron microscopy and its electrochemical properties characterised by cyclic voltammetry and electrochemical impedance spectroscopy. The enzyme tyrosinase was immobilised over the modified electrode by the drop and dry technique. Catechol was determined by direct reduction of biocatalytically formed o-quinone by employing the flow injection analysis technique. The analytical characteristics of the proposed sensor were optimised as follows: phosphate buffer 0.050 M at pH 6.5, flow rate 5.0 mL min -1 , sample injection volume 150 μL, catechol concentration 1.0 mM and maximum inhibition time by fenitrothion of 6 min. The biosensors showed a linear response to pesticide concentration from 0.018 to 3.60 μM. The limit of detection and limit of quantification were calculated as 4.70 nM and 15.9 nM (RSD < 2.7%), respectively. The intra- and inter-electrode RSDs were 3.35% (n = 15) and 8.70% (n = 7), respectively. In addition, water samples spiked with the pesticide showed an average recovery of 97.6% (±1.53). Copyright © 2018 Elsevier Inc. All rights reserved.

A Potentiometric Indirect Uric Acid Sensor Based on ZnO Nanoflakes and Immobilized Uricase

PubMed Central

Usman Ali, Syed M.; Ibupoto, Zafar Hussain; Kashif, Muhammad; Hashim, Uda; Willander, Magnus

2012-01-01

In the present work zinc oxide nanoflakes (ZnO-NF) structures with a wall thickness around 50 to 100 nm were synthesized on a gold coated glass substrate using a low temperature hydrothermal method. The enzyme uricase was electrostatically immobilized in conjunction with Nafion membrane on the surface of well oriented ZnO-NFs, resulting in a sensitive, selective, stable and reproducible uric acid sensor. The electrochemical response of the ZnO-NF-based sensor vs. a Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (500 nM to 1.5 mM). In addition, the ZnO-NF structures demonstrate vast surface area that allow high enzyme loading which results provided a higher sensitivity. The proposed ZnO-NF array-based sensor exhibited a high sensitivity of ∼66 mV/ decade in test electrolyte solutions of uric acid, with fast response time. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea. PMID:22736977

Electrochemical determination of nitrate with nitrate reductase-immobilized electrodes under ambient air.

PubMed

Quan, De; Shim, Jun Ho; Kim, Jong Dae; Park, Hyung Soo; Cha, Geun Sig; Nam, Hakhyun

2005-07-15

Nitrate monitoring biosensors were prepared by immobilizing nitrate reductase derived from yeast on a glassy carbon electrode (GCE, d = 3 mm) or screen-printed carbon paste electrode (SPCE, d = 3 mm) using a polymer (poly(vinyl alcohol)) entrapment method. The sensor could directly determine the nitrate in an unpurged aqueous solution with the aid of an appropriate oxygen scavenger: the nitrate reduction reaction driven by the enzyme and an electron-transfer mediator, methyl viologen, at -0.85 V (GCE vs Ag/AgCl) or at -0.90 V (SPCE vs Ag/AgCl) exhibited no oxygen interference in a sulfite-added solution. The electroanalytical properties of optimized biosensors were measured: the sensitivity, linear response range, and detection limit of the sensors based on GCE were 7.3 nA/microM, 15-300 microM (r2 = 0.995), and 4.1 microM (S/N = 3), respectively, and those of SPCE were 5.5 nA/microM, 15-250 microM (r2 = 0.996), and 5.5 microM (S/N = 3), respectively. The disposable SPCE-based biosensor with a built-in well- or capillary-type sample cell provided high sensor-to-sensor reproducibility (RSD < 3.4% below 250 microM) and could be used more than one month in normal room-temperature storage condition. The utility of the proposed sensor system was demonstrated by determining nitrate in real samples.

Amperometric glucose biosensor based on glucose oxidase dispersed in multiwalled carbon nanotubes/graphene oxide hybrid biocomposite.

PubMed

Palanisamy, Selvakumar; Cheemalapati, Srikanth; Chen, Shen-Ming

2014-01-01

An amperometric glucose biosensor based on enhanced and fast direct electron transfer (DET) of glucose oxidase (GOx) at enzyme dispersed multiwalled carbon nanotubes/graphene oxide (MWCNT/GO) hybrid biocomposite was developed. The fabricated hybrid biocomposite was characterized by transmission electron microscopy (TEM), Raman and infrared spectroscopy (IR). The TEM image of hybrid biocomposite reveals that a thin layer of GOx was covered on the surface of MWCNT/GO hybrid composite. IR results validate that the hybrid biocomposite was formed through the electrostatic interactions between GOx and MWCNT/GO hybrid composite. Further, MWCNT/GO hybrid composite has also been characterized by TEM and UV-visible spectroscopy. A pair of well-defined redox peak was observed for GOx immobilized at the hybrid biocomposite electrode than that immobilized at the MWCNT modified electrode. The electron transfer rate constant (Ks) of GOx at the hybrid biocomposite was calculated to be 11.22s(-1). The higher Ks value revealed that fast DET of GOx occurred at the electrode surface. Moreover, fabricated biosensor showed a good sensitivity towards glucose oxidation over a linear range 0.05-23.2mM. The limit of detection (LOD) was estimated to be 28μM. The good features of the proposed biosensor could be used for the accurate detection of glucose in the biological samples. © 2013.

Fabricating an Amperometric Cholesterol Biosensor by a Covalent Linkage between Poly(3-thiopheneacetic acid) and Cholesterol Oxidase.

PubMed

Nien, Po-Chin; Chen, Po-Yen; Ho, Kuo-Chuan

2009-01-01

In this study, use of the covalent enzyme immobilization method was proposed to attach cholesterol oxidase (ChO) on a conducting polymer, poly(3-thiopheneacetic acid), [poly(3-TPAA)]. Three red-orange poly(3-TPAA) films, named electrodes A, B and C, were electropolymerized on a platinum electrode by applying a constant current of 1.5 mA, for 5, 20 and 100 s, respectively. Further, 1-ethyl-3-(3-dimethylamiopropyl)carbodiimide hydrochloride (EDC · HCl) and N-hydroxysuccinimide (NHS) were used to activate the free carboxylic groups of the conducting polymer. Afterwards, the amino groups of the cholesterol oxidase were linked on the activated groups to form peptide bonds. The best sensitivity obtained for electrode B is 4.49 mA M(-1) cm(-2), with a linear concentration ranging from 0 to 8 mM, which is suitable for the analysis of cholesterol in humans. The response time (t(95)) is between 70 and 90 s and the limit of detection is 0.42 mM, based on the signal to noise ratio equal to 3. The interference of species such as ascorbic acid and uric acid increased to 5.2 and 10.3% of the original current response, respectively, based on the current response of cholesterol (100%). With respect to the long-term stability, the sensing response retains 88% of the original current after 13 days.

Current Status and Bioinspired Perspective of Electrochemical Conversion of CO2 to a Long-Chain Hydrocarbon.

PubMed

Yang, Ki Dong; Lee, Chan Woo; Jin, Kyoungsuk; Im, Sang Won; Nam, Ki Tae

2017-01-19

Electrocatalytic conversion of CO 2 into a long-chain hydrocarbon represents an important research direction in adding value to CO 2 -based chemicals and realizing its practical application. Long-chain hydrocarbons may change the current fossil fuel-based industry in that those chemicals have a similar energy density as gasoline, high compatibility with the current infrastructure, and low hydroscopicity for pipeline distribution. However, most of the electrocatalysts produce C 1 , C 2 , and C 3 chemicals, and methods for producing long-chain hydrocarbons are not available thus far. Interestingly, nature utilizes many enzymes to generate long-chain hydrocarbons using C 2 building blocks and suggests key mechanisms, inspiring new perspective in the design of electrocatalysts. In this Perspective, we present case studies to demonstrate how CO 2 and its reductive derivatives interact with the electrode surface during C-C bond formation and introduce how these issues are addressed in biological systems. We end this Perspective by outlining possible strategies to translate the natural mechanism into a heterogeneous electrode.

Amperometric L-lysine biosensor based on carboxylated multiwalled carbon nanotubes-SnO2 nanoparticles-graphene composite

NASA Astrophysics Data System (ADS)

Kaçar, Ceren; Erden, Pınar Esra; Kılıç, Esma

2017-10-01

A novel matrix, carboxylated multiwalled carbon nanotubes-tin oxide nanoparticles-graphene-chitosan (c-MWCNTs-SnO2-GR-CS) composite, was prepared for biosensor construction. Lysine oxidase (LOx) enzyme was immobilized covalently on the surface of c-MWCNTs-GR-SnO2-CS composite modified glassy carbon electrode (GCE) using N-ethyl-N‧-(3-dimethyaminopropyl) carbodiimide (EDC) and N-hydroxyl succinimide (NHS). Effects of electrode composition and buffer pH on biosensor response were investigated to optimize the working conditions. The biosensor exhibited wide linear range (9.9 × 10-7 M-1.6 × 10-4 M), low detection limit (1.5 × 10-7 M), high sensitivity (55.20 μA mM-1 cm-2) and fast amperometric response (<25 s) at +0.70 V vs. Ag/AgCl. With good repeatability and long-term stability, the c-MWCNTs-SnO2-GR-CS based biosensor offered an alternative for L-lysine biosensing. The practical applicability of the biosensor in two dietary supplements has also been addressed.

A novel conductometric biosensor based on hexokinase for determination of adenosine triphosphate.

PubMed

Kucherenko, I S; Kucherenko, D Yu; Soldatkin, O O; Lagarde, F; Dzyadevych, S V; Soldatkin, A P

2016-04-01

The paper presents a simple and inexpensive reusable biosensor for determination of the concentration of adenosine-5'-triphosphate (ATP) in aqueous samples. The biosensor is based on a conductometric transducer which contains two pairs of gold interdigitated electrodes. An enzyme hexokinase was immobilized onto one pair of electrodes, and bovine serum albumin-onto another pair (thus, a differential mode of measurement was used). Conditions of hexokinase immobilization on the transducer by cross-linking via glutaraldehyde were optimized. Influence of experimental conditions (concentration of magnesium ions, ionic strength and concentration of the working buffer) on the biosensor work was studied. The reproducibility of biosensor responses and operational stability of the biosensor were checked during one week. Dry storage at -18 °C was shown to be the best conditions to store the biosensor. The biosensor was successfully applied for measurements of ATP concentration in pharmaceutical samples. The proposed biosensor may be used in future for determination of ATP and/or glucose in water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Wireless Instantaneous Neurotransmitter Concentration System–based amperometric detection of dopamine, adenosine, and glutamate for intraoperative neurochemical monitoring

PubMed Central

Agnesi, Filippo; Tye, Susannah J.; Bledsoe, Jonathan M.; Griessenauer, Christoph J.; Kimble, Christopher J.; Sieck, Gary C.; Bennet, Kevin E.; Garris, Paul A.; Blaha, Charles D.; Lee, Kendall H.

2009-01-01

Object In a companion study, the authors describe the development of a new instrument named the Wireless Instantaneous Neurotransmitter Concentration System (WINCS), which couples digital telemetry with fast-scan cyclic voltammetry (FSCV) to measure extracellular concentrations of dopamine. In the present study, the authors describe the extended capability of the WINCS to use fixed potential amperometry (FPA) to measure extracellular concentrations of dopamine, as well as glutamate and adenosine. Compared with other electrochemical techniques such as FSCV or high-speed chronoamperometry, FPA offers superior temporal resolution and, in combination with enzyme-linked biosensors, the potential to monitor nonelectroactive analytes in real time. Methods The WINCS design incorporated a transimpedance amplifier with associated analog circuitry for FPA; a microprocessor; a Bluetooth transceiver; and a single, battery-powered, multilayer, printed circuit board. The WINCS was tested with 3 distinct recording electrodes: 1) a carbon-fiber microelectrode (CFM) to measure dopamine; 2) a glutamate oxidase enzyme-linked electrode to measure glutamate; and 3) a multiple enzyme-linked electrode (adenosine deaminase, nucleoside phosphorylase, and xanthine oxidase) to measure adenosine. Proof-of-principle analyses included noise assessments and in vitro and in vivo measurements that were compared with similar analyses by using a commercial hardwired electrochemical system (EA161 Picostat, eDAQ; Pty Ltd). In urethane-anesthetized rats, dopamine release was monitored in the striatum following deep brain stimulation (DBS) of ascending dopaminergic fibers in the medial forebrain bundle (MFB). In separate rat experiments, DBS-evoked adenosine release was monitored in the ventrolateral thalamus. To test the WINCS in an operating room setting resembling human neurosurgery, cortical glutamate release in response to motor cortex stimulation (MCS) was monitored using a large-mammal animal model, the pig. Results The WINCS, which is designed in compliance with FDA-recognized consensus standards for medical electrical device safety, successfully measured dopamine, glutamate, and adenosine, both in vitro and in vivo. The WINCS detected striatal dopamine release at the implanted CFM during DBS of the MFB. The DBS-evoked adenosine release in the rat thalamus and MCS-evoked glutamate release in the pig cortex were also successfully measured. Overall, in vitro and in vivo testing demonstrated signals comparable to a commercial hardwired electrochemical system for FPA. Conclusions By incorporating FPA, the chemical repertoire of WINCS-measurable neurotransmitters is expanded to include glutamate and other nonelectroactive species for which the evolving field of enzyme-linked biosensors exists. Because many neurotransmitters are not electrochemically active, FPA in combination with enzyme-linked microelectrodes represents a powerful intraoperative tool for rapid and selective neurochemical sampling in important anatomical targets during functional neurosurgery. PMID:19425899

Wireless Instantaneous Neurotransmitter Concentration System-based amperometric detection of dopamine, adenosine, and glutamate for intraoperative neurochemical monitoring.

PubMed

Agnesi, Filippo; Tye, Susannah J; Bledsoe, Jonathan M; Griessenauer, Christoph J; Kimble, Christopher J; Sieck, Gary C; Bennet, Kevin E; Garris, Paul A; Blaha, Charles D; Lee, Kendall H

2009-10-01

In a companion study, the authors describe the development of a new instrument named the Wireless Instantaneous Neurotransmitter Concentration System (WINCS), which couples digital telemetry with fast-scan cyclic voltammetry (FSCV) to measure extracellular concentrations of dopamine. In the present study, the authors describe the extended capability of the WINCS to use fixed potential amperometry (FPA) to measure extracellular concentrations of dopamine, as well as glutamate and adenosine. Compared with other electrochemical techniques such as FSCV or high-speed chronoamperometry, FPA offers superior temporal resolution and, in combination with enzyme-linked biosensors, the potential to monitor nonelectroactive analytes in real time. The WINCS design incorporated a transimpedance amplifier with associated analog circuitry for FPA; a microprocessor; a Bluetooth transceiver; and a single, battery-powered, multilayer, printed circuit board. The WINCS was tested with 3 distinct recording electrodes: 1) a carbon-fiber microelectrode (CFM) to measure dopamine; 2) a glutamate oxidase enzyme-linked electrode to measure glutamate; and 3) a multiple enzyme-linked electrode (adenosine deaminase, nucleoside phosphorylase, and xanthine oxidase) to measure adenosine. Proof-of-principle analyses included noise assessments and in vitro and in vivo measurements that were compared with similar analyses by using a commercial hardwired electrochemical system (EA161 Picostat, eDAQ; Pty Ltd). In urethane-anesthetized rats, dopamine release was monitored in the striatum following deep brain stimulation (DBS) of ascending dopaminergic fibers in the medial forebrain bundle (MFB). In separate rat experiments, DBS-evoked adenosine release was monitored in the ventrolateral thalamus. To test the WINCS in an operating room setting resembling human neurosurgery, cortical glutamate release in response to motor cortex stimulation (MCS) was monitored using a large-mammal animal model, the pig. The WINCS, which is designed in compliance with FDA-recognized consensus standards for medical electrical device safety, successfully measured dopamine, glutamate, and adenosine, both in vitro and in vivo. The WINCS detected striatal dopamine release at the implanted CFM during DBS of the MFB. The DBS-evoked adenosine release in the rat thalamus and MCS-evoked glutamate release in the pig cortex were also successfully measured. Overall, in vitro and in vivo testing demonstrated signals comparable to a commercial hardwired electrochemical system for FPA. By incorporating FPA, the chemical repertoire of WINCS-measurable neurotransmitters is expanded to include glutamate and other nonelectroactive species for which the evolving field of enzyme-linked biosensors exists. Because many neurotransmitters are not electrochemically active, FPA in combination with enzyme-linked microelectrodes represents a powerful intraoperative tool for rapid and selective neurochemical sampling in important anatomical targets during functional neurosurgery.

Construction of a biocathode using the multicopper oxidase from the hyperthermophilic archaeon, Pyrobaculum aerophilum: towards a long-life biobattery.

PubMed

Sakamoto, Hiroaki; Uchii, Toshiki; Yamaguchi, Kayo; Koto, Ayako; Takamura, Ei-Ichiro; Satomura, Takenori; Sakuraba, Haruhiko; Ohshima, Toshihisa; Suye, Shin-Ichiro

2015-07-01

The life of biobatteries remains an issue due to loss of enzyme activity over time. In this study, we sought to develop a biobattery with a long life using a hyperthermophilic enzyme. We hypothesized that use of such hyperthermophilic enzymes would allow for the biofuel cells to have a long battery life. Using pyrroloquinoline quinone-glucose dehydrogenase and the multicopper oxidase from Pyrobaculum aerophilum, we constructed an anode and cathode. The maximum output was 11 μW at 0.2 V, and the stability of the both electrode was maintained at 70 % after 14 days. The biofuel cells that use hyperthermophilic enzymes may prolong their life.

Enzyme-immobilized SiO2-Si electrode: Fast interfacial electron transfer with preserved enzymatic activity

NASA Astrophysics Data System (ADS)

Wang, Gang; Yau, Siu-Tung

2005-12-01

The enzyme, glucose oxidase (GOx), is immobilized using electrostatic interaction on the native oxide of heavily doped n-type silicon. Voltammetric measurement shows that the immobilized GOx gives rise to a very fast enzyme-silicon interfacial electron transfer rate constant of 7.9s-1. The measurement also suggests that the enzyme retains its native conformation when immobilized on the silicon surface. The preserved native conformation of GOx is further confirmed by testing the enzymatic activity of the immobilized GOx using glucose. The GOx-immobilized silicon is shown to behave as a glucose sensor that detects glucose with concentrations as low as 50μM.

Enhanced non-enzymatic glucose biosensor of Ga-doped ZnO nanorods

NASA Astrophysics Data System (ADS)

Peng, Wan-Chan; Wang, Zi-Hao; Yang, Chih-Chiang; Huang, Chien-Sheng; Su, Yan-Kuin; Ruan, Jian-Long

2017-04-01

In this work gallium (Ga)-Doped ZnO nanorods (GZO NRs) successfully applied for the development of enzyme free glucose. GZO NRs synthesized by using the hydrothermal on ZnO seed layer was subsequently deposited onto the glass substrate. The GZO NRs electrode has peak currents increasing from 620 to 941μA with glucose concentration (6, 8 and 10 mM) in cyclic voltammograms. GZO NRs electrode sensitivity of the sensor to glucose oxidation was 33.4 (μA/mM-cm2). The GZO NRs modified electrode showed a greatly enhanced electrocatalytic property toward glucose oxidation, as well as an excellent anti-interference and a good stability.

Electrochemical Affinity Biosensors Based on Disposable Screen-Printed Electrodes for Detection of Food Allergens

PubMed Central

Vasilescu, Alina; Nunes, Gilvanda; Hayat, Akhtar; Latif, Usman; Marty, Jean-Louis

2016-01-01

Food allergens are proteins from nuts and tree nuts, fish, shellfish, wheat, soy, eggs or milk which trigger severe adverse reactions in the human body, involving IgE-type antibodies. Sensitive detection of allergens in a large variety of food matrices has become increasingly important considering the emergence of functional foods and new food manufacturing technologies. For example, proteins such as casein from milk or lysozyme and ovalbumin from eggs are sometimes used as fining agents in the wine industry. Nonetheless, allergen detection in processed foods is a challenging endeavor, as allergen proteins are degraded during food processing steps involving heating or fermentation. Detection of food allergens was primarily achieved via Enzyme-Linked Immuno Assay (ELISA) or by chromatographic methods. With the advent of biosensors, electrochemical affinity-based biosensors such as those incorporating antibodies and aptamers as biorecognition elements were also reported in the literature. In this review paper, we highlight the success achieved in the design of electrochemical affinity biosensors based on disposable screen-printed electrodes towards detection of protein allergens. We will discuss the analytical figures of merit for various disposable screen-printed affinity sensors in relation to methodologies employed for immobilization of bioreceptors on transducer surface. PMID:27827963

Electrochemical Affinity Biosensors Based on Disposable Screen-Printed Electrodes for Detection of Food Allergens.

PubMed

Vasilescu, Alina; Nunes, Gilvanda; Hayat, Akhtar; Latif, Usman; Marty, Jean-Louis

2016-11-05

Food allergens are proteins from nuts and tree nuts, fish, shellfish, wheat, soy, eggs or milk which trigger severe adverse reactions in the human body, involving IgE-type antibodies. Sensitive detection of allergens in a large variety of food matrices has become increasingly important considering the emergence of functional foods and new food manufacturing technologies. For example, proteins such as casein from milk or lysozyme and ovalbumin from eggs are sometimes used as fining agents in the wine industry. Nonetheless, allergen detection in processed foods is a challenging endeavor, as allergen proteins are degraded during food processing steps involving heating or fermentation. Detection of food allergens was primarily achieved via Enzyme-Linked Immuno Assay (ELISA) or by chromatographic methods. With the advent of biosensors, electrochemical affinity-based biosensors such as those incorporating antibodies and aptamers as biorecognition elements were also reported in the literature. In this review paper, we highlight the success achieved in the design of electrochemical affinity biosensors based on disposable screen-printed electrodes towards detection of protein allergens. We will discuss the analytical figures of merit for various disposable screen-printed affinity sensors in relation to methodologies employed for immobilization of bioreceptors on transducer surface.

Ultrasensitive electrochemical sensing platform for microRNA based on tungsten oxide-graphene composites coupling with catalyzed hairpin assembly target recycling and enzyme signal amplification.

PubMed

Shuai, Hong-Lei; Huang, Ke-Jing; Xing, Ling-Li; Chen, Ying-Xu

2016-12-15

An ultrasensitive electrochemical biosensor for microRNA (miRNA) is developed based on tungsten oxide-graphene composites coupling with catalyzed hairpin assembly target recycling and enzyme signal amplification. WO3-Gr is prepared by a simple hydrothermal method and then coupled with gold nanoparticles to act as a sensing platform. The thiol-terminated capture probe H1 is immobilized on electrode through Au-S interaction. In the presence of target miRNA, H1 opens its hairpin structure by hybridization with target miRNA. This hybridization can be displaced from the structure by another stable biotinylated hairpin DNA (H2), and target miRNA is released back to the sample solution for next cycle. Thus, a large amount of H1-H2 duplex is produced after the cyclic process. At this point, a lot of signal indicators streptavidin-conjugated alkaline phosphatase (SA-ALP) are immobilized on the electrode by the specific binding of avidin-biotin. Then, thousands of ascorbic acid, which is the enzymatic product of ALP, induces the electrochemical-chemical-chemical redox cycling to produce a strongly electrochemical response in the presence of ferrocene methanol and tris (2-carboxyethyl) phosphine. Under the optimal experimental conditions, the established biosensor can detect target miRNA down to 0.05fM (S/N=3) with a linear range from 0.1fM to 100pM, and discriminate target miRNA from mismatched miRNA with a high selectivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Bio-inspired Construction of Advanced Fuel Cell Cathode with Pt Anchored in Ordered Hybrid Polymer Matrix.

PubMed

Xia, Zhangxun; Wang, Suli; Jiang, Luhua; Sun, Hai; Liu, Shuang; Fu, Xudong; Zhang, Bingsen; Sheng Su, Dang; Wang, Jianqiang; Sun, Gongquan

2015-11-05

The significant use of platinum for catalyzing the cathodic oxygen reduction reactions (ORRs) has hampered the widespread use of polymer electrolyte membrane fuel cells (PEMFCs). The construction of well-defined electrode architecture in nanoscale with enhanced utilization and catalytic performance of Pt might be a promising approach to address such barrier. Inspired by the highly efficient catalytic processes in enzymes with active centers embedded in charge transport pathways, here we demonstrate for the first time a design that allocates platinum nanoparticles (Pt NPs) at the boundaries with dual-functions of conducting both electrons by aid of polypyrrole and protons via Nafion(®) ionomer within hierarchical nanoarrays. By mimicking enzymes functionally, an impressive ORR activity and stability is achieved. Using this brand new electrode architecture as the cathode and the anode of a PEMFC, a high mass specific power density of 5.23 W mg(-1)Pt is achieved, with remarkable durability. These improvements are ascribed to not only the electron decoration and the anchoring effects from the Nafion(®) ionomer decorated PPy substrate to the supported Pt NPs, but also the fast charge and mass transport facilitated by the electron and proton pathways within the electrode architecture.

Bio-inspired Construction of Advanced Fuel Cell Cathode with Pt Anchored in Ordered Hybrid Polymer Matrix

NASA Astrophysics Data System (ADS)

Xia, Zhangxun; Wang, Suli; Jiang, Luhua; Sun, Hai; Liu, Shuang; Fu, Xudong; Zhang, Bingsen; Sheng Su, Dang; Wang, Jianqiang; Sun, Gongquan

2015-11-01

The significant use of platinum for catalyzing the cathodic oxygen reduction reactions (ORRs) has hampered the widespread use of polymer electrolyte membrane fuel cells (PEMFCs). The construction of well-defined electrode architecture in nanoscale with enhanced utilization and catalytic performance of Pt might be a promising approach to address such barrier. Inspired by the highly efficient catalytic processes in enzymes with active centers embedded in charge transport pathways, here we demonstrate for the first time a design that allocates platinum nanoparticles (Pt NPs) at the boundaries with dual-functions of conducting both electrons by aid of polypyrrole and protons via Nafion® ionomer within hierarchical nanoarrays. By mimicking enzymes functionally, an impressive ORR activity and stability is achieved. Using this brand new electrode architecture as the cathode and the anode of a PEMFC, a high mass specific power density of 5.23 W mg-1Pt is achieved, with remarkable durability. These improvements are ascribed to not only the electron decoration and the anchoring effects from the Nafion® ionomer decorated PPy substrate to the supported Pt NPs, but also the fast charge and mass transport facilitated by the electron and proton pathways within the electrode architecture.

Electrochemical detection of the MT-ND6 gene and its enzymatic digestion: application in human genomic sample.

PubMed

Mazloum-Ardakani, Mohammad; Ahmadi, Roya; Heidari, Mohammad Mehdi; Sheikh-Mohseni, Mohammad Ali

2014-06-15

A simple electrochemical biosensor was developed for the detection of the mitochondrial NADH dehydrogenase 6 gene (MT-ND6) and its enzymatic digestion by BamHI enzyme. This biosensor was fabricated by modification of a glassy carbon electrode with gold nanoparticles (AuNPs/GCE) and a probe oligonucleotide (ssDNA/AuNPs/GCE). The probe, which is a thiolated segment of the MT-ND6 gene, was deposited by self-assembling immobilization on AuNPs/GCE. Two indicators including methylene blue (MB) and neutral red (NR) were used as the electroactive indicators and the electrochemical response of the modified electrode was measured by differential pulse voltammetry. The proposed biosensor can detect the complementary sequences of the MT-ND6 gene. Also the modified electrode was used for the detection of an enzymatic digestion process by BamHI enzyme. The electrochemical biosensor can detect the MT-ND6 gene and its enzymatic digestion in polymerase chain reaction (PCR)-amplified DNA extracted from human blood. Also the biosensor was used directly for detection of the MT-ND6 gene in all of the human genome. Copyright © 2014 Elsevier Inc. All rights reserved.

Composite electrochemical biosensors: a comparison of three different electrode matrices for the construction of amperometric tyrosinase biosensors.

PubMed

Serra, B; Jiménez, S; Mena, M L; Reviejo, A J; Pingarrón, J M

2002-03-01

A comparison of the behaviour of three different rigid composite matrices for the construction of amperometric tyrosinase biosensors, which are widely used for the detection of phenolic compounds, is reported. The composite electrode matrices were, graphite-Teflon; reticulated vitreous carbon (RVC)-epoxy resin; and graphite-ethylene/propylene/diene (EPD) terpolymer. After optimization of the experimental conditions, different aspects regarding the stability of the three composite tyrosinase electrode designs were considered and compared. A better reproducibility of the amperometric responses was found with the graphite-EPD electrodes, whereas a longer useful lifetime was observed for the graphite-Teflon electrodes. The kinetic parameters of the tyrosinase reaction were calculated for eight different phenolic compounds, as well as their corresponding calibration plots. The general trend in sensitivity was graphite-EPD>graphite-Teflon>RVC-epoxy resin. A correlation between sensitivity and the catalytic efficiency of the enzyme reaction for each phenolic substrate was found. Furthermore, differences in the sensitivity order for the phenolic compounds were observed among the three biocomposite electrodes, which suggests that the nature of the electrode matrix influences the interactions in the tyrosinase catalytic cycle.

A complete carbon counter electrode for high performance quasi solid state dye sensitized solar cell

NASA Astrophysics Data System (ADS)

Arbab, Alvira Ayoub; Peerzada, Mazhar Hussain; Sahito, Iftikhar Ali; Jeong, Sung Hoon

2017-03-01

The proposed research describes the design and fabrication of a quasi-solid state dye sensitized solar cells (Q-DSSCs) with a complete carbon based counter electrode (CC-CE) and gel infused membrane electrolyte. For CE, the platinized fluorinated tin oxide glass (Pt/FTO) was replaced by the soft cationic functioned multiwall carbon nanotubes (SCF-MWCNT) catalytic layer coated on woven carbon fiber fabric (CFF) prepared on handloom by interlacing of carbon filament tapes. SCF-MWCNT were synthesized by functionalization of cationised lipase from Candida Ragusa. Cationised enzyme solution was prepared at pH ∼3 by using acetic acid. The cationic enzyme functionalization of MWCNT causes the minimum damage to the tubular morphology and assist in fast anchoring of negative iodide ions present in membrane electrolyte. The high electrocatalytic activity and low charge transfer resistance (RCT = 2.12 Ω) of our proposed system of CC-CE shows that the woven CFF coated with cationised lipase treated carbon nanotubes enriched with positive surface ions. The Q-DSSCs fabricated with CC-CE and 5 wt% PEO gel infused PVDF-HFP membrane electrolyte exhibit power conversion efficiency of 8.90% under masking. Our suggested low cost and highly efficient system of CC-CE helps the proposed quasi-solid state DSSCs structure to stand out as sustainable next generation solar cells.

Preparation and characterization of superporous agarose-reticulated vitreous carbon electrodes as platforms for electrochemical bioassays.

PubMed

Rao, Ashwin K; Creager, Stephen E

2008-08-01

Three-dimensional flow-through electrodes were fabricated using superporous agarose (SPA) and reticulated vitreous carbon (RVC) composite materials that were suitable as a platform for sandwich assays. These SPA-RVC composite electrodes were fabricated by fitting a SPA-RVC composite cylinder inside a graphite tube and subsequently fixing the graphite tube onto a polypropylene micropipette tip. The electrode design allows for ease in reagent/washing steps involved in sandwich assay protocols and could easily be made portable. The electrode materials were characterized with respect to pore-size distribution, total free volume, ligament and bulk densities of the RVC, and physical structural characteristics. Coulometric detection of redox molecules such as K(3)Fe(CN)(6) and 4-aminophenol was possible using SPA-RVC electrodes by the trapping of these redox molecules inside the SPA-RVC electrodes. Avidin affinity molecules were covalently immobilized onto the SPA matrix inside the RVC electrodes by periodate-activation followed by reductive amination. The amount of avidin immobilized inside the SPA-RVC electrodes was (5+/-0.06)x10(-11) mol, which was determined by saturating the avidin sites with biotinylated fluorescein (b-fluo) and subsequently determining the amount of immobilized b-fluo via a standard addition method using fluorescence spectroscopy. Non-specific binding of labeled enzymes such as biotinylated alkaline phosphatase (b-ALP) onto the SPA-RVC electrodes without avidin capture sites was determined to be less than 1% compared to the specific binding of b-ALP on avidinylated SPA-RVC electrodes.

Preparation of Glucose Sensor Using Polydimethylsiloxane / Polypyrrole Complex

NASA Astrophysics Data System (ADS)

Yasuzawa, Mikito; Inoue, Shigeru; Imai, Shinji

New glucose oxidase (GOD) immobilized glucose sensors were prepared by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) on the platinum wire electrode precoated with the mixture solution of pyrrole derivative GHP, polydimethylsiloxane (PDS) and Nafion. The addition of Nafion into the precoating mixture solution was essential to obtain suitable sensor sensitivity. However, the sensitivity was about the half of that of the electrode without PDS precoating. Although, the introduction of Nafion was effective to improve the long-term stability of the enzyme-immobilized electrode, the electrode prepared using Nafion, PDS and GHP performed excellent long-term stability even at the measurement and storage temperatures of 40°C. Relatively constant response current was obtained over 30 days under the condition of 40°C and over 9 months measured at 25°C. Moreover, the GOD-immobilized GHP polymer film prepared on the electrode precoated with GHP, PDS and Nafion solution, was found to have excellent hemocompatibility from the result of platelet rich plasma contacting test.

Glucose sensing based on Pt-MWCNT and MWCNT

NASA Astrophysics Data System (ADS)

Aryasomayajula, Lavanya; Xie, Jining; Wang, Shouyan; Varadan, Vijay K.

2007-04-01

It is known that multi walled carbon nanotubes (MWCNTs) is an excellent materials for biosensing applications and with the introduction of Pt nanoparticles (Pt-MWCNTs) of about 3nm in diameter in MWCNTs greatly increases the current sensitivity and also the signal to noise ratio. We fabricated the CNT- based glucose sensor by immobilization the bio enzyme, glucose oxidase (GoX), on the Pt-MWCNT and electrode were prepared. The sensor has been tested effectively for both the abnormal blood glucose levels- greater than 6.9 mM and less than 3.5 mM which are the prediabetic and diabetic glucose levels, respectively. The current signal obtained from the Pt-MWCNT was much higher compared to the MWCNT based sensors.

A novel amperometric enzyme inhibition biosensor based on xanthine oxidase immobilised onto glassy carbon electrodes for bisphenol A determination.

PubMed

Ben Messaoud, Najib; Ghica, Mariana Emilia; Dridi, Cherif; Ben Ali, Mounir; Brett, Christopher M A

2018-07-01

A novel and simple biosensor for the determination of bisphenol A (BPA) based on xanthine oxidase (XOD) enzymatic inhibition has been developed. The biosensor was prepared from xanthine oxidase immobilised by crosslinking with glutaraldehyde, with hypoxanthine as enzyme substrate, and was successfully applied to the determination of BPA using fixed potential amperometry. Biosensor performance was optimised with respect to the applied potential, influence of pH of the electrolyte solution, XOD loading and the substrate concentration. The enzyme inhibition mechanism was evaluated from Cornish-Bowden plus Dixon plots and was found to be reversible and competitive with an apparent inhibition constant of 8.15 nM. Under optimised conditions, the determination of BPA can be achieved in the linear range up to 41 nM with a detection limit of 1.0 nM, which is equal to the lowest reported in the literature, with very good repeatability and reproducibility. The selectivity of the biosensor was evaluated by performing an interference study and found to be excellent; and stability was investigated. It was successfully applied to the detection of BPA in mineral water and in river water. Copyright © 2018 Elsevier B.V. All rights reserved.

Detection of vapor-phase organophosphate threats using wearable conformable integrated epidermal and textile wireless biosensor systems.

PubMed

Mishra, Rupesh K; Martín, Aida; Nakagawa, Tatsuo; Barfidokht, Abbas; Lu, Xialong; Sempionatto, Juliane R; Lyu, Kay Mengjia; Karajic, Aleksandar; Musameh, Mustafa M; Kyratzis, Ilias L; Wang, Joseph

2018-03-15

Flexible epidermal tattoo and textile-based electrochemical biosensors have been developed for vapor-phase detection of organophosphorus (OP) nerve agents. These new wearable sensors, based on stretchable organophosphorus hydrolase (OPH) enzyme electrodes, are coupled with a fully integrated conformal flexible electronic interface that offers rapid and selective square-wave voltammetric detection of OP vapor threats and wireless data transmission to a mobile device. The epidermal tattoo and textile sensors display a good reproducibility (with RSD of 2.5% and 4.2%, respectively), along with good discrimination against potential interferences and linearity over the 90-300mg/L range, with a sensitivity of 10.7µA∙cm 3 ∙mg -1 (R 2 = 0.983) and detection limit of 12mg/L in terms of OP air density. Stress-enduring inks, used for printing the electrode transducers, ensure resilience against mechanical deformations associated with textile and skin-based on-body sensing operations. Theoretical simulations are used to estimate the OP air density over the sensor surface. These fully integrated wearable wireless tattoo and textile-based nerve-agent vapor biosensor systems offer considerable promise for rapid warning regarding personal exposure to OP nerve-agent vapors in variety of decentralized security applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanoporous Gold for Enzyme Immobilization.

PubMed

Stine, Keith J; Jefferson, Kenise; Shulga, Olga V

2017-01-01

Nanoporous gold (NPG) is a material of emerging interest for immobilization of biomolecules, especially enzymes. The material provides a high surface area form of gold that is suitable for physisorption or for covalent modification by self-assembled monolayers. The material can be used as a high surface area electrode and with immobilized enzymes can be used for amperometric detection schemes. NPG can be prepared in a variety of formats from alloys containing between 20 and 50 % atomic composition of gold and less noble element(s) by dealloying procedures. Materials resembling NPG can be prepared by hydrothermal and electrodeposition methods. Related high surface area gold structures have been prepared using templating approaches. Covalent enzyme immobilization can be achieved by first forming a self-assembled monolayer on NPG bearing a terminal reactive functional group followed by conjugation to the enzyme through amide linkages to lysine residues. Enzymes can also be entrapped by physisorption or immobilized by electrostatic interactions.

High Electromagnetic Field Enhancement of TiO2 Nanotube Electrodes.

PubMed

Öner, Ibrahim Halil; Querebillo, Christine Joy; David, Christin; Gernert, Ulrich; Walter, Carsten; Driess, Matthias; Leimkühler, Silke; Ly, Khoa Hoang; Weidinger, Inez M

2018-06-11

We present the fabrication of TiO 2 nanotube electrodes with high biocompatibility and extraordinary spectroscopic properties. Intense surface-enhanced resonance Raman signals of the heme unit of the redox enzyme Cytochrome b 5 were observed upon covalent immobilization of the protein matrix on the TiO 2 surface, revealing overall preserved structural integrity and redox behavior. The enhancement factor could be rationally controlled by varying the electrode annealing temperature, reaching a record maximum value of over 70 at 475 °C. For the first time, such high values are reported for non-directly surface-interacting probes, for which the involvement of charge-transfer processes in signal amplification can be excluded. The origin of the surface enhancement is exclusively attributed to enhanced localized electric fields resulting from the specific optical properties of the nanotubular geometry of the electrode. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fundamental studies of glucose oxidase deposition on a Pt electrode.

PubMed

Matsumoto, Norio; Chen, Xiaohong; Wilson, George S

2002-01-15

The direct electrodeposition of glucose oxidase (EC 1.1.3.4) on a platinum electrode was investigated as a means for controlled immobilization. The presence of a nonionic detergent, Triton X-100, was found essential to produce a multilayered deposit. Moreover, to work properly, the detergent must be present above its critical micelle concentration. Under these conditions, a deposit of approximately 50 enzyme layers (480 nm), with surface uniformity of +/-20 nm, was verified using an electrochemical quartz crystal microbalance and by atomic force microscopy. In the absence of detergent, a layer of 25 nm is formed. Contrary to most previous claims, the deposition, which is potential dependent but optimal at 1.3 V versus AgCl/Ag electrode, is not electrophoretically driven, but is instead controlled by a lowering of the pH at the electrode surface due to concomitant oxygen evolution.

Development of an Electrochemical Immunosensor for Fumonisins Detection in Foods

PubMed Central

Kadir, Mohamad Kamal Abdul; Tothill, Ibtisam E.

2010-01-01

An electrochemical affinity sensor for the determination of fumonisins mycotoxins (Fms) using monoclonal antibody modified screen-printed gold electrode with carbon counter and silver-silver chloride pseudo-reference electrode is reported in this work. A direct competitive enzyme-linked immunosorbent assay (ELISA) was initially developed, exhibiting a detection limit of 100 µg·L-1 for fumonisins. This was then transferred to the surface of a bare gold screen-printed electrode (SPGE) and detection was performed by chronoamperometry, monitoring the reaction of 3,3’,5,5’-Tetramethylbenzidine dihydrochloride (TMB) and hydrogen peroxide (H2O2) catalysed by HRP at −100 mV potential vs. onboard Ag-AgCl pseudo-reference electrode. The immunosensor exhibited detection limit of 5 µg·L−1 fumonisins with a dynamic range from 1 µg·L−1–1000 µg·L−1. The sensor also performed well in extracted corn samples. PMID:22069591

SCREEN-PRINTED TYROSINASE-CONTAINING ELECTRODES FOR THE BIOSENSING OF ENZYME INHIBITORS

EPA Science Inventory

Disposal amperometric inhibition biosensors have been microfabricated by screen printing a tyrosinase-containing carbon ink. The decrease in the substrate (catechol) steady-state current, caused by the addition of various pesticides and herbicides, offers convenient quantitation ...

Direct Comparison of the Performance of a Bio-inspired Synthetic Nickel Catalyst and a [NiFe]-Hydrogenase, Both Covalently Attached to Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez-Macia, Patricia; Dutta, Arnab; Lubitz, Wolfgang

2015-10-12

The active site of hydrogenases has been a source of inspiration for the development of molecular catalysts. However, direct comparisons between molecular catalysts and enzymes have not been possible because different techniques are used to evaluate both types of catalysts, minimizing our ability to determine how far we’ve come in mimicking the impressive enzymatic performance. Here we directly compare the catalytic properties of the [Ni(PCy2NGly2)2]2+ complex with the [NiFe]-hydrogenase from Desulfobivrio vulgaris Miyazaki F (DvMF) immobilized to a functionalized electrode under identical conditions. At pH=7, the enzyme has higher performance in both activity and overpotential, and is more stable, whilemore » at low pH, the molecular catalyst outperforms the enzyme in all respects. The Ni complex also has increased tolerance to CO. This is the first direct comparison of enzymes and molecular complexes, enabling a unique understanding of the benefits and detriments of both systems, and advancing our understanding of the utilization of these bioinspired complexes in fuel cells. AD and WJS acknowledge the Office of Science Early Career Research Program through the US Department of Energy (US DOE), Office of Science, Office of Basic Energy Sciences (BES), and Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the US DOE.« less

A performance comparison of choline biosensors: anodic or cathodic detections of H2O2 generated by enzyme immobilized on a conducting polymer.

PubMed

Rahman, Md Aminur; Park, Deog-Soo; Shim, Yoon-Bo

2004-07-15

Amperometric choline biosensors were fabricated by the covalent immobilization of an enzyme of choline oxidase (ChO) and a bi-enzyme of ChO/horseradish peroxidase (ChO/HRP) onto poly-5,2':5',2"-terthiophene-3'-carboxylic acid (poly-TTCA) modified electrodes (CPMEs). A sensor modified with ChO utilized the oxidation process of enzymatically generated H(2)O(2) in a choline solution at +0.6V. The other one modified with ChO/HRP utilized the reduction process of H(2)O(2) in a choline solution at -0.2V. Experimental parameters affecting the sensitivity of sensors, such as pH, applied potential, and temperature were optimized. A performance comparison of two sensors showed that one based on ChO/HRP/CPME had a linear range from 1.0 x 10(-6) to 8.0 x 10(-5) M and the other based on ChO/CPME from 1.0 x 10(-6) to 5.0 x 10(-5) M. The detection limits for choline employing ChO/HRP/CPME and ChO/CPME were determined to be about 1.0 x 10(-7) and 4.0 x 10(-7) M, respectively. The response time of sensors was less than 5s. Sensors showed good selectivity to interfering species. The long-term storage stability of the sensor based on ChO/HRP/CPME was longer than that based on ChO/CPME.

Permselective and enzyme-entrapping behaviours of an electropolymerized, non-conducting, poly(o-aminophenol) thin film-modified electrode: a critical study.

PubMed

Guerrieri, Antonio; Ciriello, Rosanna; Centonze, Diego

2009-02-15

Non-conducting polymeric films synthesised by the electrooxidation of o-aminophenol on a platinum electrode in acetate or phosphate buffer displayed an interesting permselective behaviour, which proved valuable in minimising the electrochemical interferences from ascorbate, acetaminophen, cysteine and urate sample molecules in amperometric detection mode. The electrosynthesis of poly(o-aminophenol) (p(oAP)) film showed also useful as permselective membrane for enzyme immobilization as demonstrated by the production of an interference-free glucose oxidase biosensor. In this respect, the glucose response time, t(0.95), evaluated in batch addition experiments, was lower than 5s while the calibration curve was linear up to 10mM of glucose with a sensitivity of 69.7nA/mM. Both the permselective behaviour and the enzyme-entrapping property of the film were critically compared with the relevant studies until now reported. With respect to the sophisticated but complex approaches described elsewhere, this study shows that simply a proper optimization of p(oAP) electrosynthesis and its permselective behaviour is the key to improve significantly the selectivity of the resulting analytical devices.

Porous NiCo2O4 nanoarray-integrated binder-free 3D open electrode offers a highly efficient sensing platform for enzyme-free glucose detection.

PubMed

Luo, X; Huang, M; He, D; Wang, M; Zhang, Y; Jiang, P

2018-05-29

High electrical conductivity and the exposure to more active sites are crucial to boost the performance of a glucose sensor. A porous binary metal oxide nanoarray integrated on a binder-free 3D electrode is expected to offer a highly sensitive sensing platform. As a model, porous NiCo2O4 nanowire arrays supported on carbon cloth (NiCo2O4 NWA/CC) have been prepared and used for enzyme-free glucose sensing. NiCo2O4 NWA/CC shows larger effective surface area, superior electronic conductivity, and higher catalytic activity towards enzyme-free glucose sensing, with a linear range from 1 μM to 0.63 mM, a sensitivity of 4.12 mA mM-1 cm-2, and low detection limit of 0.5 μM. Moreover, NiCo2O4 NWA/CC also displays good selectivity and stability and thus, it can be reliable for glucose detection in human serum samples. These findings inspire the fabrication of a high-performance electrochemical sensing platform by preparing porous binary metal oxide nanoarrays supported on a 3D conductive substrate.

Genome Scale Mutational Analysis of Geobacter sulfurreducens Reveals Distinct Molecular Mechanisms for Respiration and Sensing of Poised Electrodes versus Fe(III) Oxides.

PubMed

Chan, Chi Ho; Levar, Caleb E; Jiménez-Otero, Fernanda; Bond, Daniel R

2017-10-01

Geobacter sulfurreducens generates electrical current by coupling intracellular oxidation of organic acids to the reduction of proteins on the cell surface that are able to interface with electrodes. This ability is attributed to the bacterium's capacity to respire other extracellular electron acceptors that require contact, such as insoluble metal oxides. To directly investigate the genetic basis of electrode-based respiration, we constructed Geobacter sulfurreducens transposon-insertion sequencing (Tn-Seq) libraries for growth, with soluble fumarate or an electrode as the electron acceptor. Libraries with >33,000 unique insertions and an average of 9 insertions/kb allowed an assessment of each gene's fitness in a single experiment. Mutations in 1,214 different genomic features impaired growth with fumarate, and the significance of 270 genes unresolved by annotation due to the presence of one or more functional homologs was determined. Tn-Seq analysis of -0.1 V versus standard hydrogen electrode (SHE) electrode-grown cells identified mutations in a subset of genes encoding cytochromes, processing systems for proline-rich proteins, sensory networks, extracellular structures, polysaccharides, and metabolic enzymes that caused at least a 50% reduction in apparent growth rate. Scarless deletion mutants of select genes identified via Tn-Seq revealed a new putative porin-cytochrome conduit complex ( extABCD ) crucial for growth with electrodes, which was not required for Fe(III) oxide reduction. In addition, four mutants lacking components of a putative methyl-accepting chemotaxis-cyclic dinucleotide sensing network ( esnABCD ) were defective in electrode colonization but grew normally with Fe(III) oxides. These results suggest that G. sulfurreducens possesses distinct mechanisms for recognition, colonization, and reduction of electrodes compared to Fe(III) oxides. IMPORTANCE Since metal oxide electron acceptors are insoluble, one hypothesis is that cells sense and reduce metals using the same molecular mechanisms used to form biofilms on electrodes and produce electricity. However, by simultaneously comparing thousands of Geobacter sulfurreducens transposon mutants undergoing electrode-dependent respiration, we discovered new cytochromes and chemosensory proteins supporting growth with electrodes that are not required for metal respiration. This supports an emerging model where G. sulfurreducens recognizes surfaces and forms conductive biofilms using mechanisms distinct from those used for growth with metal oxides. These findings provide a possible explanation for studies that correlate electricity generation with syntrophic interspecies electron transfer by Geobacter and reveal many previously unrecognized targets for engineering this useful capability in other organisms. Copyright © 2017 Chan et al.

Gold nanoparticles-decorated silver-bipyridine nanobelts for the construction of mediatorless hydrogen peroxide biosensor.

PubMed

Boujakhrout, Abderrahmane; Díez, Paula; Sánchez, Alfredo; Martínez-Ruíz, Paloma; Pingarrón, José M; Villalonga, Reynaldo

2016-11-15

Au nanoparticles modified with 4-mercaptopyridine and 6-mercapto-1-hexanol were used as coordination agents to prepare a novel hybrid nanomaterial with Ag:4,4'-bipyridine nanobelts. This nanohybrid was employed to modify glassy carbon electrodes and to construct a horseradish peroxidase-based mediatorless amperometric biosensor for H2O2. The electrode, poised at -100mV, exhibited a rapid response within 4s and a linear calibration range from 90pM to 6.5nM H2O2. The biosensor showed a high sensitivity of 283A/Mcm(2) and a very low detection limit of 45pM at a signal-to-noise ratio of 3. The enzyme biosensor showed high stability when stored at 4°C under dry conditions, retaining over 96% and 78% of its initial activity after 15 and 30days of storage at 4°C, respectively. Copyright © 2016 Elsevier Inc. All rights reserved.

Extended Gate Field-Effect Transistor Biosensors for Point-Of-Care Testing of Uric Acid.

PubMed

Guan, Weihua; Reed, Mark A

2017-01-01

An enzyme-free redox potential sensor using off-chip extended-gate field effect transistor (EGFET) with a ferrocenyl-alkanethiol modified gold electrode has been used to quantify uric acid concentration in human serum and urine. Hexacyanoferrate (II) and (III) ions are used as redox reagent. The potentiometric sensor measures the interface potential on the ferrocene immobilized gold electrode, which is modulated by the redox reaction between uric acid and hexacyanoferrate ions. The device shows a near Nernstian response to uric acid and is highly specific to uric acid in human serum and urine. The interference that comes from glucose, bilirubin, ascorbic acid, and hemoglobin is negligible in the normal concentration range of these interferents. The sensor also exhibits excellent long term reliability and is regenerative. This extended gate field effect transistor based sensor is promising for point-of-care detection of uric acid due to the small size, low cost, and low sample volume consumption.

Construction of conducting polymer/cytochrome C/thylakoid membrane based photo-bioelectrochemical fuel cells generating high photocurrent via photosynthesis.

PubMed

Cevik, Emre; Carbas, Buket Bezgin; Senel, Mehmet; Yildiz, Huseyin Bekir

2018-08-15

In this study, a photo-bioelectrochemical fuel cell was constructed for photocurrent generation by illuminating the electrodes within an aqueous solution. In this purpose, gold electrode was coated with poly 4-(4H-Dithieno [3,2-b:2',3'-d]pyrol-4-yl) aniline, P(DTP-Ph-NH 2 ) conductive polymer film by using electrochemical polymerization. Then, P(DTP-Ph-NH 2 ) conductive polymer film coated surface was electrochemically modified with cytochrome C which covalently linked onto the surface via bis-aniline functionality of the polymer film and formed crosslinked-structure. The thylakoid membrane was attached on the surface of this electrode by using bissulfosaxinimidyl suberate (BS 3 ) and used as photo-anode in photo-bioelectrochemical fuel cell. The photo-cathode of the photo-bioelectrochemical fuel cell fabrication was followed by the modification of conductive polymer poly[5-(4H-dithieno [3,2-b:2',3'-d]pyrol-4-yl) naphtalene-1-amine] film coating, glutaraldehyde activation, and bilirubin oxidase enzyme immobilization. During the photosynthesis occurring in thylakoid membrane under the light, water was oxidized and separated; while oxygen was released in anode side, the cathode side was reduced the oxygen gas into the water via a bio-electro-catalytic method. The cytochrome C was used for binding of thylakoid membrane to the electrode surface and play an important role for transferring of electrons released as a result of photosynthesis. Copyright © 2018 Elsevier B.V. All rights reserved.

Construction of an amperometric ascorbate biosensor using epoxy resin membrane bound Lagenaria siceraria fruit ascorbate oxidase.

PubMed

Pundir, C S; Chauhan, Nidhi; Jyoti

2011-06-01

Ascorbate oxidase purified from Lagenaria siceraria fruit was immobilized onto epoxy resin "Araldite" membrane with 79.4% retention of initial activity of free enzyme. The biosensor showed optimum response within 15s at pH 5.8 and 35°C, which was directly proportional to ascorbate concentration ranging from 1-100μM. There was a good correlation (R(2) = 0.99) between serum ascorbic acid values by standard enzymic colorimetric method and the present method. The enzyme electrode was used for 200 times without considerable loss of activity during the span of 90 days when stored at 4°C.

Amperometric immunosensor based on multiwalled carbon nanotubes/Prussian blue/nanogold-modified electrode for determination of α-fetoprotein.

PubMed

Jiang, Wen; Yuan, Ruo; Chai, Ya-Qin; Yin, Bing

2010-12-01

In this article, a conspicuously simple and highly sensitive amperometric immunosensor based on the sequential electrodeposition of Prussian blue (PB) and gold nanoparticles (GNPs) on multiwalled carbon nanotube (MWCNT)-modified glassy carbon electrode (GCE) surface is proposed for the detection of α-fetoprotein (AFP). By comparison with PB, the MWCNT/PB composite film had been proven to show much better electrochemical stability and a larger response current. The electrodeposited GNP film can be used not only to immobilize biomolecules but also to avoid the leakage of PB and to prevent shedding of MWCNT/PB composite film from the electrode surface. The performance and factors influencing the performance of the immunosensor were investigated. Under optimal experimental conditions, the proposed immunosensor for AFP was observed with an ultralow limit of detection (LOD) equal to 3 pg/ml (at 3δ), and the linear working range spanned the concentrations of AFP from 0.01 to 300 ng/ml. Moreover, the immunosensor, as well as a commercially available kit, was examined for use in the determination of AFP in real human serum specimens. More significant, the assay mentioned here is simpler than the traditional enzyme-linked immunosorbent assay (ELISA), and an excellent correlation of levels of AFP measured was obtained, indicating that the developed immunoassay could be a promising alternative approach for detection of AFP and other tumor markers in the clinical diagnosis. Copyright © 2010 Elsevier Inc. All rights reserved.

Ultrasensitive signal-on DNA biosensor based on nicking endonuclease assisted electrochemistry signal amplification.

PubMed

Liu, Zhongyuan; Zhang, Wei; Zhu, Shuyun; Zhang, Ling; Hu, Lianzhe; Parveen, Saima; Xu, Guobao

2011-11-15

Combining the advantages of signal-on strategy and nicking endonuclease assisted electrochemistry signal amplification (NEAESA), a new sensitive and signal-on electrochemical DNA biosensor for the sequence specific DNA detection based on NEAESA has been developed for the first time. A Hairpin-shape probe (HP), containing the target DNA recognition sequence, is thiol-modified at 5' end and immobilized on gold electrode via Au-S bonding. Subsequently, the HP modified electrode is hybridized with target DNA to form a duplex. Then the nicking endonuclease is added and nicks the HP strand in the duplex. After nicking, 3'-ferrocene (Fc)-labeled part complementary probe (Fc-PCP) is introduced on the electrode surface by hybridizing with the thiol-modified HP fragment, which results in the generation of electrochemical signal. Hence, the DNA biosensor is constructed successfully. The present DNA biosensor shows a wide linear range of 5.0×10(-13)-5.0×10(-8)M for detecting target DNA, with a low detection limit of 0.167pM. The proposed strategy does not require any amplifying labels (enzymes, DNAzymes, nanoparticles, etc.) for biorecognition events, which avoids false-positive results to occur frequently. Moreover, the strategy has the benefits of simple preparation, convenient operation, good selectivity, and high sensitivity. With the advantages mentioned above, this simple and sensitive strategy has the potential to be integrated in portable, low cost and simplified devices for diagnostic applications. Copyright © 2011 Elsevier B.V. All rights reserved.

Electrical Microengineering of Redox Enzymes

DTIC Science & Technology

1994-03-31

coating applied to the electrode 41 to prevent lose of mediator graphite foil potassium -~0.02a 0.03  electrolyte wus dioxane with 15% 42...hexacyanoferrats(ll)d aqueous buffer carbon fiber’ none h 40-5000 biotin/avidin complex used to obtain a 43 surface layer of HRP Pt organic metal, potassium ...OFFICE OF NAVAL RESEARCH AD-A279 015 FINAL REPORT FOR CONTRACT NOOO 14-91 -J- 1656 R&T CODE 413h007---05 ELECTRICAL MICROENGINEERING OF REDOX ENZYMES

The Effects of Repeated Low-Dose Sarin Exposure

DTIC Science & Technology

2005-08-01

support the idea that there is a triphasic NT model for onset and progression of seizures and subsequent brain damage upon acute exposure to OP ChE...An ACh microbore column (1x530 mm ID, 10 µm UniJet, BAS #MF-8904) coupled with AChE/choline oxidase immobilized enzyme reactor (BAS # MF-8903) was...peroxidase to the electrode for the reduction of hydrogen peroxide that was generated from the immobilized enzyme reactor . The detector was set at (-)1.0

Electrochemical biosensor based on enzyme substrate as a linker: Application for aldolase activity with pectin-thionine complex as recognization element and signal amplification probe.

PubMed

Wang, Xiaonan; Wang, Meiwen; Zhang, Yuanyuan; Miao, Xiaocao; Huang, Yuanyuan; Zhang, Juan; Sun, Lizhou

2016-09-15

A new strategy to fabricate electrochemical biosensor is reported based on the linkage of enzyme substrate, thereby an electrochemical method to detect aldolase activity is established using pectin-thionine complex (PTC) as recognization element and signal probe. The linkage effect of fructose-1,6-bisphosphate (FBP), the substrate of aldolase, can be achieved via its strong binding to magnetic nanoparticles (MNPs)/aminophenylboronic acid (APBA) and the formation of phosphoramidate bond derived from its reaction with p-phenylenediamine (PDA) on the surface of electrode. Aldolase can reversibly catalyze the substrates into the products which have no binding capacity with MNPs/APBA, resulting in the exposure of the corresponding binding sites and its subsequent recognization on signal probe. Meanwhile, signal amplification can be accomplished by using the firstly prepared PTC which can bind with MNPs/APBA, and accuracy can be strengthened through magnetic separation. With good precision and accuracy, the established sensor may be extended to other proteins with reversible catalyzed ability. Copyright © 2016 Elsevier B.V. All rights reserved.

Nitrogen-Doped Carbon Nanotubes Supported by Macroporous Carbon as an Efficient Enzymatic Biosensing Platform for Glucose.

PubMed

Song, Yonghai; Lu, Xingping; Li, Yi; Guo, Qiaohui; Chen, Shuiliang; Mao, Lanqun; Hou, Haoqing; Wang, Li

2016-01-19

Effective immobilization of enzymes/proteins on an electrode surface is very essential for biosensor development, but it still remains challenging because enzymes/proteins tend to form close-packed structures on the electrode surface. In this work, nitrogen-doped carbon nanotubes (NCNTs) supported by three-dimensional Kenaf Stem-derived porous carbon (3D-KSC) (denoted as 3D-KSC/NCNTs) nanocomposites were constructed as the supporting matrix to load glucose oxidase (GOD) for preparing integrated glucose biosensors. These NCNTs are vertically arrayed on the channel walls of the 3D-KSC via the chemical vapor deposition method, which could noticeably increase the effective surface area, mechanical stability, and active sites (originating from the doped nitrogen) of the nanocomposites. The integrated glucose biosensor exhibits some advantages over the traditional GOD electrodes in terms of the capability to promote the direct electron transfer of GOD, enhance the mechanical stability of the biosensor attributed to the strong interaction between NCNTs and GOD, and enlarge the specific surface area to efficiently load a large number of GODs. The as-prepared biosensor shows a good performance toward both oxygen reduction and glucose biosensing. This study essentially offers a novel approach for the development of biosensors with excellent analytical properties.

Fabrication and characterization of electrochemically prepared bioanode (polyaniline/ferritin/glucose oxidase) for biofuel cell application

NASA Astrophysics Data System (ADS)

ul Haque, Sufia; Inamuddin; Nasar, Abu; Asiri, Abdullah M.

2018-01-01

Porous matrix of polyaniline (PANI) has been electrodeposited along with the entrapment of biocompatible redox mediator ferritin (Frt) and glucose oxidase (GOx) on the surface of glassy carbon (GC) electrode. The characterizations have been carried out by X-ray Diffraction (XRD) and Transmission electron microscopy (TEM). The enhanced electrochemical signal transfer rate from enzyme to the electrode surface was due to the intimate contact of the enzyme with the electrochemically polymerized conducting PANI matrix. The PANI/Frt/GOx modified GC bioanode was used to investigate the electrocatalytic activity as a function of the concentration of glucose in the range of 10-60 mM. It was confirmed by the electrochemical impedance spectroscopy (EIS), the thick deposition of PANI layer becomes more compact due to which the charge transfer resistance of PANI matrix becomes higher. All the electrochemical measurements of the electrode were carried out by using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). CV curves were recorded at different scan rates (20-100 mV/s) at 50 mM of glucose in 0.3 M potassium ferrocyanide. A normalized saturation current density of 22.3 ± 2 mA/cm2 was observed for the oxidation of 50 mM glucose at a scan rate of 100 mV/s.

Bio-inspired Construction of Advanced Fuel Cell Cathode with Pt Anchored in Ordered Hybrid Polymer Matrix

PubMed Central

Xia, Zhangxun; Wang, Suli; Jiang, Luhua; Sun, Hai; Liu, Shuang; Fu, Xudong; Zhang, Bingsen; Sheng Su, Dang; Wang, Jianqiang; Sun, Gongquan

2015-01-01

The significant use of platinum for catalyzing the cathodic oxygen reduction reactions (ORRs) has hampered the widespread use of polymer electrolyte membrane fuel cells (PEMFCs). The construction of well-defined electrode architecture in nanoscale with enhanced utilization and catalytic performance of Pt might be a promising approach to address such barrier. Inspired by the highly efficient catalytic processes in enzymes with active centers embedded in charge transport pathways, here we demonstrate for the first time a design that allocates platinum nanoparticles (Pt NPs) at the boundaries with dual-functions of conducting both electrons by aid of polypyrrole and protons via Nafion® ionomer within hierarchical nanoarrays. By mimicking enzymes functionally, an impressive ORR activity and stability is achieved. Using this brand new electrode architecture as the cathode and the anode of a PEMFC, a high mass specific power density of 5.23 W mg−1Pt is achieved, with remarkable durability. These improvements are ascribed to not only the electron decoration and the anchoring effects from the Nafion® ionomer decorated PPy substrate to the supported Pt NPs, but also the fast charge and mass transport facilitated by the electron and proton pathways within the electrode architecture. PMID:26537781

Lipase-nanoporous gold biocomposite modified electrode for reliable detection of triglycerides.

PubMed

Wu, Chao; Liu, Xueying; Li, Yufei; Du, Xiaoyu; Wang, Xia; Xu, Ping

2014-03-15

For triglycerides biosensor design, protein immobilization is necessary to create the interface between the enzyme and the electrode. In this study, a glassy carbon electrode (GCE) was modified with lipase-nanoporous gold (NPG) biocomposite (denoted as lipase/NPG/GCE). Due to highly conductive, porous, and biocompatible three-dimensional structure, NPG is suitable for enzyme immobilization. In cyclic voltammetry experiments, the lipase/NPG/GCE bioelectrode displayed surface-confined reaction in a phosphate buffer solution. Linear responses were obtained for tributyrin concentrations ranging from 50 to 250 mg dl(-1) and olive oil concentrations ranging from 10 to 200 mg dl(-1). The value of apparent Michaelis-Menten constant for tributyrin was 10.67 mg dl(-1) and the detection limit was 2.68 mg dl(-1). Further, the lipase/NPG/GCE bioelectrode had strong anti-interference ability against urea, glucose, cholesterol, and uric acid as well as a long shelf-life. For the detection of triglycerides in human serum, the values given by the lipase/NPG/GCE bioelectrode were in good agreement with those of an automatic biochemical analyzer. These properties along with a long self-life make the lipase/NPG/GCE bioelectrode an excellent choice for the construction of triglycerides biosensor. © 2013 Elsevier B.V. All rights reserved.

Novel nanoarchitectures for electrochemical biosensing

NASA Astrophysics Data System (ADS)

Archibald, Michelle M.

Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point-of-care (POC) technologies. Current methods, while sensitive, do not adequately allow for POC applications due to several limitations, including complex instrumentation, high reagent consumption, and cost. We have investigated two novel nanoarchitectures, the nanocoax and the nanodendrite, as electrochemical biosensors towards the POC detection of infectious disease biomarkers to overcome these limitations. The nanocoax architecture is composed of vertically-oriented, nanoscale coaxial electrodes, with coax cores and shields serving as integrated working and counter electrodes, respectively. The dendritic structure consists of metallic nanocrystals extending from the working electrode, increasing sensor surface area. Nanocoaxial- and nanodendritic-based electrochemical sensors were fabricated and developed for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV). Proof-of-concept was demonstrated for the detection of cholera toxin (CT). Both nanoarchitectures exhibited levels of sensitivity that are comparable to the standard optical ELISA used widely in clinical applications. In addition to matching the detection profile of the standard ELISA, these electrochemical nanosensors provide a simple electrochemical readout and a miniaturized platform with multiplexing capabilities toward POC implementation. Further development as suggested in this thesis may lead to increases in sensitivity, enhancing the attractiveness of the architectures for future POC devices.

Highly Sensitive and Selective Immuno-capture/Electrochemical Assay of Acetylcholinesterase Activity in Red Blood Cells: A Biomarker of Exposure to Organophosphorus Pesticides and Nerve Agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Aiqiong; Du, Dan; Lin, Yuehe

Acetylcholinesterase (AChE) enzyme activity in red blood cells (RBCs) is a useful biomarker for biomonitoring of exposures to organophosphorus (OP) pesticides and chemical nerve agents. In this paper, we reported a new method for AChE activity assay based on selective immuno-capture of AChE from biological samples followed by enzyme activity assay of captured AChE using a disposable electrochemical sensor. The electrochemical sensor is based on multiwalled carbon nanotubes-gold nanocomposites (MWCNTs-Au) modified screen printed carbon electrode (SPCE). Upon the completion of immunoreaction, the target AChE (including active and inhibited) is captured onto the electrode surface and followed by an electrochemical detectionmore » of enzymatic activity in the presence of acetylthiocholine. A linear response is obtained over standard AChE concentration range from 0.1 to 10 nM. To demonstrate the capability of this new biomonitoring method, AChE solutions dosed with different concentration of paraoxon were used to validate the new AChE assay method. AChE inhibition in OP dosed solutions was proportional to its concentration from 0.2 to 50 nM. The new AChE activity assay method for biomonitoring of OP exposure was further validated with in-vitro paraoxon-dosed RBC samples. The established electrochemical sensing platform for AChE activity assay not only avoids the problem of overlapping substrate specificity with esterases by using selective antibody, but also eliminates potential interference from other electroactive species in biological samples. It offers a new approach for sensitive, selective, and rapid AChE activity assay for biomonitoring of exposures to OPs.« less

Droplet-based pyrosequencing using digital microfluidics.

PubMed

Boles, Deborah J; Benton, Jonathan L; Siew, Germaine J; Levy, Miriam H; Thwar, Prasanna K; Sandahl, Melissa A; Rouse, Jeremy L; Perkins, Lisa C; Sudarsan, Arjun P; Jalili, Roxana; Pamula, Vamsee K; Srinivasan, Vijay; Fair, Richard B; Griffin, Peter B; Eckhardt, Allen E; Pollack, Michael G

2011-11-15

The feasibility of implementing pyrosequencing chemistry within droplets using electrowetting-based digital microfluidics is reported. An array of electrodes patterned on a printed-circuit board was used to control the formation, transportation, merging, mixing, and splitting of submicroliter-sized droplets contained within an oil-filled chamber. A three-enzyme pyrosequencing protocol was implemented in which individual droplets contained enzymes, deoxyribonucleotide triphosphates (dNTPs), and DNA templates. The DNA templates were anchored to magnetic beads which enabled them to be thoroughly washed between nucleotide additions. Reagents and protocols were optimized to maximize signal over background, linearity of response, cycle efficiency, and wash efficiency. As an initial demonstration of feasibility, a portion of a 229 bp Candida parapsilosis template was sequenced using both a de novo protocol and a resequencing protocol. The resequencing protocol generated over 60 bp of sequence with 100% sequence accuracy based on raw pyrogram levels. Excellent linearity was observed for all of the homopolymers (two, three, or four nucleotides) contained in the C. parapsilosis sequence. With improvements in microfluidic design it is expected that longer reads, higher throughput, and improved process integration (i.e., "sample-to-sequence" capability) could eventually be achieved using this low-cost platform.

Droplet-Based Pyrosequencing Using Digital Microfluidics

PubMed Central

Boles, Deborah J.; Benton, Jonathan L.; Siew, Germaine J.; Levy, Miriam H.; Thwar, Prasanna K.; Sandahl, Melissa A.; Rouse, Jeremy L.; Perkins, Lisa C.; Sudarsan, Arjun P.; Jalili, Roxana; Pamula, Vamsee K.; Srinivasan, Vijay; Fair, Richard B.; Griffin, Peter B.; Eckhardt, Allen E.; Pollack, Michael G.

2013-01-01

The feasibility of implementing pyrosequencing chemistry within droplets using electrowetting-based digital microfluidics is reported. An array of electrodes patterned on a printed-circuit board was used to control the formation, transportation, merging, mixing, and splitting of submicroliter-sized droplets contained within an oil-filled chamber. A three-enzyme pyrosequencing protocol was implemented in which individual droplets contained enzymes, deoxyribonucleotide triphosphates (dNTPs), and DNA templates. The DNA templates were anchored to magnetic beads which enabled them to be thoroughly washed between nucleotide additions. Reagents and protocols were optimized to maximize signal over background, linearity of response, cycle efficiency, and wash efficiency. As an initial demonstration of feasibility, a portion of a 229 bp Candida parapsilosis template was sequenced using both a de novo protocol and a resequencing protocol. The resequencing protocol generated over 60 bp of sequence with 100% sequence accuracy based on raw pyrogram levels. Excellent linearity was observed for all of the homopolymers (two, three, or four nucleotides) contained in the C. parapsilosis sequence. With improvements in microfluidic design it is expected that longer reads, higher throughput, and improved process integration (i.e., “sample-to-sequence” capability) could eventually be achieved using this low-cost platform. PMID:21932784

Functionalized graphene oxide for clinical glucose biosensing in urine and serum samples

PubMed Central

Veerapandian, Murugan; Seo, Yeong-Tai; Shin, Hyunkyung; Yun, Kyusik; Lee, Min-Ho

2012-01-01

A novel clinical glucose biosensor fabricated using functionalized metalloid-polymer (silver-silica coated with polyethylene glycol) hybrid nanoparticles on the surface of a graphene oxide nanosheet is reported. The cyclic voltammetric response of glucose oxidase modification on the surface of a functionalized graphene oxide electrode showed a surface-confined reaction and an effective redox potential near zero volts, with a wide linearity of 0.1–20 mM and a sensitivity of 7.66 μA mM−1 cm−2. The functionalized graphene oxide electrode showed a better electrocatalytic response toward oxidation of H2O2 and reduction of oxygen. The practical applicability of the functionalized graphene oxide electrode was demonstrated by measuring the peak current against multiple urine and serum samples from diabetic patients. This new hybrid nanoarchitecture combining a three-dimensional metalloid-polymer hybrid and two-dimensional graphene oxide provided a thin solid laminate on the electrode surface. The easy fabrication process and retention of bioactive immobilized enzymes on the functionalized graphene oxide electrode could potentially be extended to detection of other biomolecules, and have broad applications in electrochemical biosensing. PMID:23269871

Functionalized graphene oxide for clinical glucose biosensing in urine and serum samples.

PubMed

Veerapandian, Murugan; Seo, Yeong-Tai; Shin, Hyunkyung; Yun, Kyusik; Lee, Min-Ho

2012-01-01

A novel clinical glucose biosensor fabricated using functionalized metalloid-polymer (silver-silica coated with polyethylene glycol) hybrid nanoparticles on the surface of a graphene oxide nanosheet is reported. The cyclic voltammetric response of glucose oxidase modification on the surface of a functionalized graphene oxide electrode showed a surface-confined reaction and an effective redox potential near zero volts, with a wide linearity of 0.1-20 mM and a sensitivity of 7.66 μA mM(-1) cm(-2). The functionalized graphene oxide electrode showed a better electrocatalytic response toward oxidation of H(2)O(2) and reduction of oxygen. The practical applicability of the functionalized graphene oxide electrode was demonstrated by measuring the peak current against multiple urine and serum samples from diabetic patients. This new hybrid nanoarchitecture combining a three-dimensional metalloid-polymer hybrid and two-dimensional graphene oxide provided a thin solid laminate on the electrode surface. The easy fabrication process and retention of bioactive immobilized enzymes on the functionalized graphene oxide electrode could potentially be extended to detection of other biomolecules, and have broad applications in electrochemical biosensing.

A Nanocoaxial-Based Electrochemical Sensor for the Detection of Cholera Toxin

NASA Astrophysics Data System (ADS)

Archibald, Michelle; Rizal, Binod; Connolly, Timothy; Burns, Michael J.; Naughton, Michael J.; Chiles, Thomas C.; Biology; Physics Collaboration

We report a nanocoax-based electrochemical sensor for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV). The device architecture is composed of vertically-oriented, nanoscale coaxial electrodes, with coax cores and shields serving as integrated working and counter electrodes, respectively. Proof-of-concept was demonstrated for the detection of cholera toxin (CT), with a linear dynamic range of detection was 10 ng/ml - 1 µg/ml, and a limit of detection (LOD) of 2 ng/ml. This level of sensitivity is comparable to the standard optical ELISA used widely in clinical applications. The nanocoax array thus matches the detection profile of the standard ELISA while providing a simple electrochemical readout and a miniaturized platform with multiplexing capabilities, toward point-of-care (POC) implementation. In addition, next generation nanocoax devices with extended cores are currently under development, which would provide a POC platform amenable for biofunctionalization of ELISA receptor proteins directly onto the device. This work was supported by the National Institutes of Health (National Cancer Institute Award No. CA137681 and National Institute of Allergy and Infectious Diseases Award No. AI100216).

Recent trends in carbon nanomaterial-based electrochemical sensors for biomolecules: A review

PubMed Central

Yang, Cheng; Denno, Madelaine E.; Pyakurel, Poojan; Venton, B. Jill

2015-01-01

Carbon nanomaterials are advantageous for electrochemical sensors because they increase the electroactive surface area, enhance electron transfer, and promote adsorption of molecules. Carbon nanotubes (CNTs) have been incorporated into electrochemical sensors for biomolecules and strategies have included the traditional dip coating and drop casting methods, direct growth of CNTs on electrodes and the use of CNT fibers and yarns made exclusively of CNTs. Recent research has also focused on utilizing many new types of carbon nanomaterials beyond CNTs. Forms of graphene are now increasingly popular for sensors including reduced graphene oxide, carbon nanohorns, graphene nanofoams, graphene nanorods, and graphene nanoflowers. In this review, we compare different carbon nanomaterial strategies for creating electrochemical sensors for biomolecules. Analytes covered include neurotransmitters and neurochemicals, such as dopamine, ascorbic acid, and serotonin; hydrogen peroxide; proteins, such as biomarkers; and DNA. The review also addresses enzyme-based electrodes that are used to detect non-electroactive species such as glucose, alcohols, and proteins. Finally, we analyze some of the future directions for the field, pointing out gaps in fundamental understanding of electron transfer to carbon nanomaterials and the need for more practical implementation of sensors. PMID:26320782

Selenium containing conducting polymer based pyranose oxidase biosensor for glucose detection.

PubMed

Gokoglan, Tugba Ceren; Soylemez, Saniye; Kesik, Melis; Toksabay, Sinem; Toppare, Levent

2015-04-01

A novel amperometric pyranose oxidase (PyOx) biosensor based on a selenium containing conducting polymer has been developed for the glucose detection. For this purpose, a conducting polymer; poly(4,7-bis(thieno[3,2-b]thiophen-2-yl)benzo[c][1,2,5] selenadiazole) (poly(BSeTT)) was synthesized via electropolymerisation on gold electrode to examine its matrix property for glucose detection. For this purpose, PyOx was used as the model enzyme and immobilised via physical adsorption technique. Amperometric detection of consumed oxygen was monitored at -0.7 V vs Ag reference electrode in a phosphate buffer (50 mM, pH 7.0). K(M)(app), Imax, LOD and sensitivity were calculated as 0.229 mM, 42.37 nA, 3.3 × 10(-4)nM and 6.4 nA/mM cm(2), respectively. Scanning electron microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS) and cyclic voltammetry (CV) techniques were used to monitor changes in surface morphologies and to run electrochemical characterisations. Finally, the constructed biosensor was applied for the determination of glucose in beverages successfully. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recent trends in carbon nanomaterial-based electrochemical sensors for biomolecules: A review.

PubMed

Yang, Cheng; Denno, Madelaine E; Pyakurel, Poojan; Venton, B Jill

2015-08-05

Carbon nanomaterials are advantageous for electrochemical sensors because they increase the electroactive surface area, enhance electron transfer, and promote adsorption of molecules. Carbon nanotubes (CNTs) have been incorporated into electrochemical sensors for biomolecules and strategies have included the traditional dip coating and drop casting methods, direct growth of CNTs on electrodes and the use of CNT fibers and yarns made exclusively of CNTs. Recent research has also focused on utilizing many new types of carbon nanomaterials beyond CNTs. Forms of graphene are now increasingly popular for sensors including reduced graphene oxide, carbon nanohorns, graphene nanofoams, graphene nanorods, and graphene nanoflowers. In this review, we compare different carbon nanomaterial strategies for creating electrochemical sensors for biomolecules. Analytes covered include neurotransmitters and neurochemicals, such as dopamine, ascorbic acid, and serotonin; hydrogen peroxide; proteins, such as biomarkers; and DNA. The review also addresses enzyme-based electrodes that are used to detect non-electroactive species such as glucose, alcohols, and proteins. Finally, we analyze some of the future directions for the field, pointing out gaps in fundamental understanding of electron transfer to carbon nanomaterials and the need for more practical implementation of sensors. Copyright © 2015 Elsevier B.V. All rights reserved.

[Development and application of electroanalytical methods in biomedical fields].

PubMed

Kusu, Fumiyo

2015-01-01

To summarize our electroanalytical research in the biomedical field over the past 43 years, this review describes studies on specular reflection measurement, redox potential determination, amperometric acid sensing, HPLC with electrochemical detection, and potential oscillation across a liquid membrane. The specular reflection method was used for clarifying the adsorption of neurotransmitters and their related drugs onto a gold electrode and the interaction between dental alloys and compound iodine glycerin. A voltammetric screening test using a redox potential for the antioxidative effect of flavonoids was proposed. Amperometric acid sensing based on the measurement of the reduction prepeak current of 2-methyl-1,4-naphthoquinone (VK3) or 3,5-di-tert-buty1-1,2-benzoquinone (DBBQ) was applied to determine acid values of fats and oils, titrable acidity of coffee, and enzyme activity of lipase, free fatty acids (FFAs) in serum, short-chain fatty acids in feces, etc. The electrode reactions of phenothiazines, catechins, and cholesterol were applied to biomedical analysis using HPLC with electrochemical detection. A three-channel electrochemical detection system was utilized for the sensitive determination of redox compounds in Chinese herbal medicines. The behavior of barbituric acid derivatives was examined based on potential oscillation measurements.

Highly sensitive and selective cholesterol biosensor based on direct electron transfer of hemoglobin.

PubMed

Zhao, Changzhi; Wan, Li; Jiang, Li; Wang, Qin; Jiao, Kui

2008-12-01

A cholesterol biosensor based on direct electron transfer of a hemoglobin-encapsulated chitosan-modified glassy carbon electrode has been developed for highly sensitive and selective analysis of serum samples. Modified by films containing hemoglobin and cholesterol oxidase, the electrode was prepared by encapsulation of enzyme in chitosan matrix. The hydrogen peroxide produced by the catalytic oxidation of cholesterol by cholesterol oxidase was reduced electrocatalytically by immobilized hemoglobin and used to obtain a sensitive amperometric response to cholesterol. The linear response of cholesterol concentrations ranged from 1.00 x 10(-5) to 6.00 x 10(-4) mol/L, with a correlation coefficient of 0.9969 and estimated detection limit of cholesterol of 9.5 micromol/L at a signal/noise ratio of 3. The cholesterol biosensor can efficiently exclude interference by the commonly coexisting ascorbic acid, uric acid, dopamine, and epinephrine. The sensitivity to the change in the concentration of cholesterol as the slope of the calibration curve was 0.596 A/M. The relative standard deviation was under 4.0% (n=5) for the determination of real samples. The biosensor is satisfactory in the determination of human serum samples.

Facile synthesis of tetragonal columnar-shaped TiO2 nanorods for the construction of sensitive electrochemical glucose biosensor.

PubMed

Yang, Zhanjun; Tang, Yan; Li, Juan; Zhang, Yongcai; Hu, Xiaoya

2014-04-15

A tetragonal columnar-shaped TiO2 (TCS-TiO2) nanorods are synthesized via a facile route for the immobilization of glucose oxidase (GOx). A novel electrochemical glucose biosensor is constructed based on the direct electrochemistry of GOx at TCS-TiO2 modified glassy carbon electrode. The fabricated biosensor is characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, electrochemical impedance spectra and cyclic voltammetry. The immobilized enzyme molecules on TCS-TiO2 nanorods retain its native structure and bioactivity and show a surface controlled, quasi-reversible and fast electron transfer process. The TCS-TiO2 nanorods have large surface area and provide a favorable microenvironment for enhancing the electron transfer between enzyme and electrode surface. The constructed glucose biosensor shows wide linear range from 5.0×10(-6) to 1.32×10(-3) M with a high sensitivity of 23.2 mA M(-1) cm(-2). The detection limit is calculated to be 2.0×10(-6) M at signal-to-noise of 3. The proposed glucose biosensor also exhibits excellent selectivity, good reproducibility, and acceptable operational stability. Furthermore, the biosensor can be successfully applied in the detection of glucose in serum sample at the applied potential of -0.50 V. The TCS-TiO2 nanorods provide an efficient and promising platform for the immobilization of proteins and development of excellent biosensors. © 2013 Published by Elsevier B.V.

A novel mesoporous silica nanosphere matrix for the immobilization of proteins and their applications as electrochemical biosensor.

PubMed

Li, Juan; Qin, Xingzhang; Yang, Zhanjun; Qi, Huamei; Xu, Qin; Diao, Guowang

2013-01-30

A mesoporous silica nanoshpere (MSN) was proposed to modify glassy carbon electrode (GCE) for the immobilization of protein. Using glucose oxidase (GOD) as a model, direct electrochemistry of protein and biosensing at the MSN modified GCE was studied for the first time. The MNS had large surface area and offered a favorable microenvironment for facilitating the direct electron transfer between enzyme and electrode surface. Scanning electron microscopy, transmission electron microscopy, UV-vis spectroscopy and cyclic voltammetry were used to examine the interaction between GOD and the MSN matrix. The results demonstrated that the immobilized enzyme on the MSN retained its native structure and bioactivity. In addition, the electrochemical reaction showed a surface controlled, reversible two-proton and two-electron transfer process with the apparent electron transfer rate constant of 3.96 s(-1). The MNS-based glucose biosensor exhibited the two linear ranges of 0.04-2.0 mM and 2.0-4.8 mM, a high sensitivity of 14.5 mA M(-1) cm(-2) and a low detection limit of 0.02 mM at signal-to-noise of 3. The proposed biosensor showed excellent selectivity, good reproducibility, acceptable stability and could be successfully applied in the reagentless detection of glucose in real samples at -0.45 V. The work displayed that mesoporous silica nanosphere provided a promising approach for immobilizing proteins and fabrication of excellent biosensors. Copyright © 2012 Elsevier B.V. All rights reserved.

New electrochemiluminescent biosensors combining polyluminol and an enzymatic matrix.

PubMed

Sassolas, Audrey; Blum, Loïc J; Leca-Bouvier, Béatrice D

2009-06-01

Performant reagentless electrochemiluminescent (ECL) (bio)sensors have been developed using polymeric luminol as the luminophore. The polyluminol film is obtained by cyclic voltammetry (CV) on a screen-printed electrode either in a commonly used H(2)SO(4) medium or under more original near-neutral buffered conditions. ECL responses obtained after performing polymerization either at acidic pH or at pH 6 have been compared. It appears that polyluminol formed in near-neutral medium gives the best responses for hydrogen peroxide detection. Polymerization at pH 6 by cyclic voltammetry gives a linear range extending from 8 x 10(-8) to 1.3 x 10(-4) M H(2)O(2) concentrations. Based on this performant sensor for hydrogen peroxide detection, an enzymatic biosensor has been developed by associating the polyluminol film with an H(2)O(2)-producing oxidase. Here, choline oxidase (ChOD) has been chosen as a model enzyme. To develop the biosensor, luminol has been polymerized at pH 6 by CV, and then an enzyme-entrapping matrix has been formed on the above modified working electrode. Different biological (chitosan, agarose, and alginate) and chemical (silica gels, photopolymers, or reticulated matrices) gels have been tested. Best performances have been obtained by associating a ChOD-immobilizing photopolymer with the polyluminol film. In this case, choline can be detected with a linear range extending from 8 x 10(-8) to 1.3 x 10(-4) M.

2D transition metal carbide MXene as a robust biosensing platform for enzyme immobilization and ultrasensitive detection of phenol.

PubMed

Wu, Lingxia; Lu, Xianbo; Dhanjai; Wu, Zhong-Shuai; Dong, Yanfeng; Wang, Xiaohui; Zheng, Shuanghao; Chen, Jiping

2018-06-01

MXene-Ti 3 C 2 , as a new class of two-dimensional (2D) transition metal carbides (or nitrides), has been synthesized by exfoliating pristine Ti 3 AlC 2 phases with hydrofluoric acid. The SEM and XRD images show that the resultant MXene possesses a graphene-like 2D nanostructure. and the surface of MXene has been partially terminated with -OH, thus providing a favorable microenvironment for enzyme immobilization and retaining their bioactivity and stability. Considering the unique metallic conductivity, biocompatibility and good dispersion in aqueous phase, the as-prepared MXene was explored as a new matrix to immobilize tyrosinase (a model enzyme) for fabricating a mediator-free biosensor for ultrasensitive and rapid detection of phenol. The varying electrochemical measurements were used to investigate the electrochemical performance of MXene-based tyrosinase biosensors. The results revealed that the direct electron transfer between tyrosinase and electrode could be easily achieved via a surface-controlled electrochemical process. The fabricated MXene-based tyrosinase biosensors exhibited good analytical performance over a wide linear range from 0.05 to 15.5 μmol L -1 , with a low detection limit of 12 nmol L -1 and a sensitivity of 414.4 mA M -1 . The proposed biosensing approach also demonstrated good repeatability, reproducibility, long-term stability and high recovery for phenol detection in real water samples. With those excellent performances, MXene with graphene-like structure is proved to be a robust and versatile electrochemical biosensing platform for enzyme-based biosensors and biocatalysis, and has wide potential applications in biomedical detection and environmental analysis. Copyright © 2018. Published by Elsevier B.V.

Mediatorless glucose biosensor and direct electron transfer type glucose/air biofuel cell enabled with carbon nanodots.

PubMed

Zhao, Mei; Gao, Yue; Sun, Junyong; Gao, Feng

2015-03-03

Utilization of carbon nanodots (CNDs), newcomers to the world of carbonaceous nanomaterials, in the electrochemistry realm has rarely been reported so far. In this study, CNDs were used as immobilization supports and electron carriers to promote direct electron transfer (DET) reactions of glucose oxidase (GOx) and bilirubin oxidase (BOD). At the CNDs electrode entrapped with GOx, a high rate constant (k(s)) of 6.28 ± 0.05 s(-1) for fast DET and an apparent Michaelis-Menten constant (K(M)(app)) as low as 0.85 ± 0.03 mM for affinity to glucose were found. By taking advantage of its excellent direct bioelectrocatalytic performances to glucose oxidation, a DET-based biosensor for glucose detection ranging from 0 to 0.64 mM with a high sensitivity of 6.1 μA mM(-1) and a limit of detection (LOD) of 1.07 ± 0.03 μM (S/N = 3) was proposed. Additionally, the promoted DET of BOD immobilized on CNDs was also observed and effectively catalyzed the reduction of oxygen to water at the onset potential of +0.51 V (vs Ag/AgCl). On the basis of the facilitated DET of these two enzymes at CNDs electrodes, a mediator-free DET-type glucose/air enzymatic biofuel cell (BFC), in which CNDs electrodes entrapped with GOx and BOD were employed for oxidizing glucose at the bioanode and reducing oxygen at the biocathode, respectively, was successfully fabricated. The constructed BFC displayed an open-circuit voltage (OCV) as high as 0.93 V and a maximum power density of 40.8 μW cm(-2) at 0.41 V. These important features of CNDs have implied to be promising materials for immobilizing enzymes and efficient platforms for elaborating bioelectrochemical devices such as biosensors and BFCs.

A comparative study of enzyme immobilization strategies for multi-walled carbon nanotube glucose biosensors

NASA Astrophysics Data System (ADS)

Shi, Jin; Claussen, Jonathan C.; McLamore, Eric S.; Haque, Aeraj ul; Jaroch, David; Diggs, Alfred R.; Calvo-Marzal, Percy; Rickus, Jenna L.; Porterfield, D. Marshall

2011-09-01

This work addresses the comparison of different strategies for improving biosensor performance using nanomaterials. Glucose biosensors based on commonly applied enzyme immobilization approaches, including sol-gel encapsulation approaches and glutaraldehyde cross-linking strategies, were studied in the presence and absence of multi-walled carbon nanotubes (MWNTs). Although direct comparison of design parameters such as linear range and sensitivity is intuitive, this comparison alone is not an accurate indicator of biosensor efficacy, due to the wide range of electrodes and nanomaterials available for use in current biosensor designs. We proposed a comparative protocol which considers both the active area available for transduction following nanomaterial deposition and the sensitivity. Based on the protocol, when no nanomaterials were involved, TEOS/GOx biosensors exhibited the highest efficacy, followed by BSA/GA/GOx and TMOS/GOx biosensors. A novel biosensor containing carboxylated MWNTs modified with glucose oxidase and an overlying TMOS layer demonstrated optimum efficacy in terms of enhanced current density (18.3 ± 0.5 µA mM - 1 cm - 2), linear range (0.0037-12 mM), detection limit (3.7 µM), coefficient of variation (2%), response time (less than 8 s), and stability/selectivity/reproducibility. H2O2 response tests demonstrated that the most possible reason for the performance enhancement was an increased enzyme loading. This design is an excellent platform for versatile biosensing applications.

The Vital Function of Fe3O4@Au nanocomposites for Hydrolase Biosensor Design and Its Application in Detection of Methyl Parathion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Yuting; Zhang, Weiying; Lin, Yuehe

A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic Fe3O4 core was synthesized using cysteamine (SH–NH2) as linker, and characterized by TEM, XPS, UV and electrochemistry. Then a hydrolase biosensor, based on self-assembly of methyl parathion hydrolase (MPH) on the Fe3O4@Au nanocomposite, was developed for sensitive and selective detection of the organophosphorus pesticide (OP) methyl parathion. The magnetic nanocomposite provides an easy way to construct the enzyme biosensor by simply exerting an external magnetic field, and also provides a simple way to renew the electrode surface by removing the magnet. Unlike inhibition-based enzyme biosensors, the hydrolase is not poisoned bymore » OPs and thus is reusable for continuous measurement. AuNPs not only provide a large surface area, high loading efficiency and fast electron transfer, but also stabilize the enzyme through electrostatic interactions. The MPH biosensor shows rapid response and high selectivity for detection of methyl parathion, with a linear range from 0.5 to 1000 ng/mL and a detection limit of 0.1 ng/mL. It also shows acceptable reproducibility and stability. The simplicity and ease of operation of the proposed method has great potential for on-site detection of P–S containing pesticides and provides a promising strategy to construct a robust biosensor.« less

Glucose Fuel Cells with a MicroChannel Fabricated on Flexible Polyimide Film

NASA Astrophysics Data System (ADS)

Sano, Ryohei; Fukushi, Yudai; Sasaki, Tsubasa; Mogi, Hiroshi; Koide, Syohei; Ikoma, Ryuta; Akatsuka, Wataru; Tsujimura, Seiya; Nishioka, Yasushiro

2013-12-01

In this work, a glucose fuel cell was fabricated using microfabrication processes assigned for microelectromechanical systems. The fuel cell was equipped with a microchannel to flow an aqueous solution of glucose. The cell was fabricated on a flexible polyimide substrate, and its porous carbon-coated aluminum (Al) electrodes of 2.8 mm in width and 11 mm in length were formed using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Al electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. The microchannel with a depth of 200 μm was fabricated using a hot embossing technique. A maximum power of 0.45 μW at 0.5 V that corresponds to a power density of 1.45 μW/cm2 was realized by introducing a 200 mM concentrated glucose solution at room temperature.

Fabrication of a sensing module using micromachined biosensors.

PubMed

Suzuki, H; Arakawa, H; Karube, I

2001-12-01

Micromachining is a powerful tool in constructing micro biosensors and micro systems which incorporate them. A sensing module for blood components was fabricated using the technology. The analytes include glucose, urea, uric acid, creatine, and creatinine. Transducers used to construct the corresponding sensors were a Severinghaus-type carbon dioxide electrode for the urea sensor and a Clark-type oxygen electrode for the other analytes. In these electrodes, detecting electrode patterns were formed on a glass substrate by photolithography and the micro container for the internal electrolyte solution was formed on a silicon substrate by anisotropic etching. A through-hole was formed in the sensitive area, where a silicone gas-permeable membrane was formed and an enzyme was immobilized. The sensors were characterized in terms of pH and temperature dependence and calibration curves along with detection limits. Furthermore, the sensors were incorporated in an acrylate flow cell. Simultaneous operation of these sensors was successfully conducted and distinct and stable responses were observed for respective sensors.

Molecular lego for the assembly of biosensing layers.

PubMed

Mano, N; Kuhn, A

2005-03-31

We propose a procedure to assemble monolayers of redox mediator, coenzyme, enzyme and stabilizing polyelectrolyte on an electrode surface using essentially electrostatic and complexing interactions. In a first step a monolayer of redox mediator, substituted nitrofluorenones, is adsorbed. In a second step, a layer of calcium cations is immobilized at the interface. It establishes a bridge between the redox mediator and the subsequently adsorbed coenzyme NAD(+). In the next step we use the intrinsic affinity of the NAD(+) monolayer for dehydrogenases to build up a multilayer composed of mediator/Ca(2+)/NAD(+)/dehydrogenase. The so obtained modified electrode can be used as a biosensor. Quartz crystal microbalance measurements allowed us to better understand the different parameters responsible for the adsorption. A more detailed investigation of the system made it possible to finally stabilize the assembly sufficiently by the adsorption of a polyelectrolyte layer in order to perform rotating disk electrode measurements with the whole supramolecular architecture on the electrode surface.

Immobilization of flavin adenine dinucleotide (FAD) onto carbon cloth and its application as working electrode in an electroenzymatic bioreactor.

PubMed

Jayabalan, R; Sathishkumar, M; Jeong, E S; Mun, S P; Yun, S E

2012-11-01

A high porosity carbon cloth with immobilized FAD was employed as working electrode in electrochemical NADH-regeneration procedure. Carbon cloth was oxidized with hot acids to create surface carboxyl group and then coupled by adenine amino group of FAD with carbodiimide in the presence of N-hydroxysulfosuccinimide. The bioelectrocatalytic NADH-regeneration was coupled to the conversion of achiral substrate pyruvate into chiral product l-lactate by l-lactate dehydrogenase (l-LDH) within the same reactor. The conversion was completed at 96h in bioreactor with FAD-modified carbon cloth, resulting in about 6mM of l-lactate from 10mM of pyruvate. While with bare carbon cloth, the yield at 120h was around 5mM. Immobilized FAD on the surface of carbon cloth electrode facilitated it to carry electrons from electrode to electron transfer enzymes; thereby NADH-regeneration was accelerated to drive the enzymatic reaction efficiently. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electrochemical detection of uric acid via uricase-immobilized graphene oxide.

PubMed

Omar, Muhamad Nadzmi; Salleh, Abu Bakar; Lim, Hong Ngee; Ahmad Tajudin, Asilah

2016-09-15

Measurement of the uric acid level in the body can be improved by biosensing with respect to the accuracy, sensitivity and time consumption. This study has reported the immobilization of uricase onto graphene oxide (GO) and its function for electrochemical detection of uric acid. Through chemical modification of GO using 1-ethyl-3-(dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHS) as cross-linking reagents, the enzyme activity of the immobilized uricase was much comparable to the free enzyme with 88% of the activity retained. The modified GO-uricase (GOU) was then subjected to electrocatalytic detection of uric acid (UA) via cyclic voltammetry (CV). For that reason, a glassy carbon electrode (GCE) was modified by adhering the GO along with the immobilized uricase to facilitate the redox reaction between the enzyme and the substrate. The modified GOU/GCE outperformed a bare electrode through the electrocatalytic activity with an amplified electrical signal for the detection of UA. The electrocatalytic response showed a linear dependence on the UA concentration ranging from 0.02 to 0.49 mM with a detection limit of 3.45 μM at 3σ/m. The resulting biosensor also exhibited a high selectivity towards UA in the presence of other interference as well as good reproducibility. Copyright © 2016 Elsevier Inc. All rights reserved.

Determination of uric acid level by polyaniline and poly (allylamine): Based biosensor

PubMed Central

Wathoni, Nasrul; Hasanah, Aliya Nur; Gozali, Dolih; Wahyuni, Yeni; Fauziah, Lia Layusa

2014-01-01

The uric acid biosensor has been much developed by immobilizing uricase enzyme into the membrane of conductive polymer and the membrane of polyelectrolyte such as polyaniline (PANI) and poly (allylamine) (PAA) respectively. The purpose of this research was to create a new amperometric uric acid biosensor by immobilization of uricase in combination between PANI and PAA membranes. The working electrode was Pt plate (0.5 mm). The auxiliary and the reference electrode were Pt wire 0.4 mm and Ag/AgCl respectively. Uricase, uric acid, PAA, pyrrole and glutaraldehyde were supplied from Sigma. All other chemical was obtained from Merck. The biosensor was created by immobilizing of uricase by a glutaraldehyde crosslinking procedure on PANI composite film on the surface of a platinum electrode while the polyelectrolyte layer of PAA were prepared via layer-by-layer assembly on the electrode, functioning as H2O2-selective film. Standard of deviation, coefficient of variation (CV) and coefficient of correlation (r) analysis were used in this study. The biosensor had a good linearity with a correlation coefficient of 0.993 and it could be used up to 27 times with the CV value of 3.97%. The presence of other compounds such as glucose and ascorbic acid gave 1.3 ± 1.13% and 3.27 ± 2.29% respectively on the interference effect toward the current response of uric acid biosensor. The polymer combination of PANI and PAA can be used as a selective matrix of uric acid biosensor. PMID:24696812

A highly efficient nano-cluster artificial peroxidase and its direct electrochemistry on a nano complex modified glassy carbon electrode.

PubMed

Hong, Jun; Wang, Wei; Huang, Kun; Yang, Wei-Yun; Zhao, Ying-Xue; Xiao, Bao-Lin; Gao, Yun-Fei; Moosavi-Movahedi, Zainab; Ghourchian, Hedayatollah; Moosavi-Movahedi, Ali Akbar

2012-01-01

A nano-cluster with highly efficient peroxide activity was constructed based on nafion (NF) and cytochrome c (Cyt c). UV-Vis spectrometry and transmission electron microscopy (TEM) methods were utilized for characterization of the nano-structured enzyme or artificial peroxidase (AP). The nano-cluster was composed of a Chain-Ball structure, with an average ball size of about 40 nm. The Michaelis-Menten (K(m)) and catalytic rate (k(cat)) constants of the AP were determined to be 2.5 ± 0.4 µM and 0.069 ± 0.001 s(-1), respectively, in 50 mM PBS at pH 7.0. The catalytic efficiency of the AP was evaluated to be 0.028 ± 0.005 µM(-1) s(-1), which was 39 ± 5% as efficient as the native horseradish peroxidase (HRP). The AP was also immobilized on a functional multi-wall carbon nanotube (MWNCTs)-gold colloid nanoparticles (AuNPs) nano-complex modified glassy carbon (GC) electrode. The cyclic voltammetry of AP on the nano complex modified GC electrode showed a pair of well-defined redox peaks with a formal potential (E°') of -45 ± 2 mV (vs. Ag/AgCl) at a scan rate of 0.05 V/s. The heterogeneous electron transfer rate constant (k(s)) was evaluated to be 0.65 s(-1). The surface concentration of electroactive AP on GC electrode (Γ) was 7 × 10(-10) mol cm(-2). The apparent Michaelis-Menten constant (K(m)(app)) was 0.23 nM.

Fabrication of nanoporous thin-film working electrodes and their biosensing applications.

PubMed

Li, Tingjie; Jia, Falong; Fan, Yaxi; Ding, Zhifeng; Yang, Jun

2013-04-15

Electrochemical detection for point-of-care diagnostics is of great interest due to its high sensitivity, fast analysis time and ability to operate on a small scale. Herein, we report the fabrication of a nanoporous thin-film electrode and its application in the configuration of a simple and robust enzymatic biosensor. The nanoporous thin-film was formed in a planar gold electrode through an alloying/dealloying process. The nanoporous electrode has an electroactive surface area up to 40 times higher than that of a flat gold electrode of the same size. The nanoporous electrode was used as a substrate to build an enzymatic electrochemical biosensor for the detection of glucose in standard samples and control serum samples. The example glucose biosensor has a linear response up to 30 mM, with a high sensitivity of 0.50 μA mM⁻¹ mm⁻², and excellent anti-interference ability against lactate, uric acid and ascorbic acid. Abundant catalyst and enzyme were stably entrapped in the nanoporous structure, leading to high stability and reproducibility of the biosensor. Development of such nanoporous structure enables the miniaturization of high-performance electrochemical biosensors for point-of-care diagnostics or environmental field testing. Copyright © 2012 Elsevier B.V. All rights reserved.

Guiding Principles of Hydrogenase Catalysis Instigated and Clarified by Protein Film Electrochemistry.

PubMed

Armstrong, Fraser A; Evans, Rhiannon M; Hexter, Suzannah V; Murphy, Bonnie J; Roessler, Maxie M; Wulff, Philip

2016-05-17

Protein film electrochemistry (PFE) is providing cutting-edge insight into the chemical principles underpinning biological hydrogen. Attached to an electrode, many enzymes exhibit "reversible" electrocatalytic behavior, meaning that a catalyzed redox reaction appears reversible or quasi-reversible when viewed by cyclic voltammetry. This efficiency is most relevant for enzymes that are inspiring advances in renewable energy, such as hydrogen-activating and CO2-reducing enzymes. Exploiting the rich repertoire of available instrumental methods, PFE experiments yield both a general snapshot and fine detail, all from tiny samples of enzyme. The dynamic electrochemical investigations blaze new trails and add exquisite detail to the information gained from structural and spectroscopic studies. This Account describes recent investigations of hydrogenases carried out in Oxford, including ideas initiated with PFE and followed through with complementary techniques, all contributing to an eventual complete picture of fast and efficient H2 activation without Pt. By immobilization of an enzyme on an electrode, catalytic electron flow and the chemistry controlling it can be addressed at the touch of a button. The buried nature of the active site means that structures that have been determined by crystallography or spectroscopy are likely to be protected, retained, and fully relevant in a PFE experiment. An electrocatalysis model formulated for the PFE of immobilized enzymes predicts interesting behavior and gives insight into why some hydrogenases are H2 producers and others are H2 oxidizers. Immobilization also allows for easy addition and removal of inhibitors along with precise potential control, one interesting outcome being that formaldehyde forms a reversible complex with reduced [FeFe]-hydrogenases, thereby providing insight into the order of electron and proton transfers. Experiments on O2-tolerant [NiFe]-hydrogenases show that O2 behaves like a reversible inhibitor: it is also a substrate, and implicit in the description of some hydrogenases as "H2/O2 oxidoreductases" is the hypothesis that fast and efficient multielectron transfer is a key to O2 tolerance because it promotes complete reduction of O2 to harmless water. Not only is a novel [4Fe-3S] cluster (able to transfer two electrons consecutively) an important component, but connections to additional electron sources (other Fe-S clusters, an electrode, another quaternary structure unit, or the physiological membrane itself) ensure that H2 oxidation can be sustained in the presence of O2, as demonstrated with enzyme fuel cells able to operate on a H2/air mixture. Manipulating the H-H bond in the active site is the simplest proton-coupled electron-transfer reaction to be catalyzed by an enzyme. Unlike small molecular catalysts or the surfaces of materials, metalloenzymes are far better suited to engineering the all-important outer-coordination shell. Hence, recent successful site-directed mutagenesis of the conserved outer-shell "canopy" residues in a [NiFe]-hydrogenase opens up new opportunities for understanding the mechanism of H2 activation beyond the role of the inner coordination shell.

Paper‐Based Electrodes for Flexible Energy Storage Devices

PubMed Central

Yao, Bin; Zhang, Jing; Kou, Tianyi; Song, Yu; Liu, Tianyu

2017-01-01

Paper‐based materials are emerging as a new category of advanced electrodes for flexible energy storage devices, including supercapacitors, Li‐ion batteries, Li‐S batteries, Li‐oxygen batteries. This review summarizes recent advances in the synthesis of paper‐based electrodes, including paper‐supported electrodes and paper‐like electrodes. Their structural features, electrochemical performances and implementation as electrodes for flexible energy storage devices including supercapacitors and batteries are highlighted and compared. Finally, we also discuss the challenges and opportunity of paper‐based electrodes and energy storage devices. PMID:28725532

Continuous non-invasive blood glucose monitoring by spectral image differencing method

NASA Astrophysics Data System (ADS)

Huang, Hao; Liao, Ningfang; Cheng, Haobo; Liang, Jing

2018-01-01

Currently, the use of implantable enzyme electrode sensor is the main method for continuous blood glucose monitoring. But the effect of electrochemical reactions and the significant drift caused by bioelectricity in body will reduce the accuracy of the glucose measurements. So the enzyme-based glucose sensors need to be calibrated several times each day by the finger-prick blood corrections. This increases the patient's pain. In this paper, we proposed a method for continuous Non-invasive blood glucose monitoring by spectral image differencing method in the near infrared band. The method uses a high-precision CCD detector to switch the filter in a very short period of time, obtains the spectral images. And then by using the morphological method to obtain the spectral image differences, the dynamic change of blood sugar is reflected in the image difference data. Through the experiment proved that this method can be used to monitor blood glucose dynamically to a certain extent.

Design of experiments and principal component analysis as approaches for enhancing performance of gas-diffusional air-breathing bilirubin oxidase cathode

NASA Astrophysics Data System (ADS)

Babanova, Sofia; Artyushkova, Kateryna; Ulyanova, Yevgenia; Singhal, Sameer; Atanassov, Plamen

2014-01-01

Two statistical methods, design of experiments (DOE) and principal component analysis (PCA) are employed to investigate and improve performance of air-breathing gas-diffusional enzymatic electrodes. DOE is utilized as a tool for systematic organization and evaluation of various factors affecting the performance of the composite system. Based on the results from the DOE, an improved cathode is constructed. The current density generated utilizing the improved cathode (755 ± 39 μA cm-2 at 0.3 V vs. Ag/AgCl) is 2-5 times higher than the highest current density previously achieved. Three major factors contributing to the cathode performance are identified: the amount of enzyme, the volume of phosphate buffer used to immobilize the enzyme, and the thickness of the gas-diffusion layer (GDL). PCA is applied as an independent confirmation tool to support conclusions made by DOE and to visualize the contribution of factors in individual cathode configurations.

Amperometric Choline Biosensor Fabricated through Electrostatic Assembly of Bienzyme/Polyelectrolyte Hybrid Layers on Carbon Nanotubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jun; Liu, Guodong; Lin, Yuehe

2006-03-01

We report a flow injection amperometric choline biosensors based on the electrostatic assembly of an enzyme of choline oxidase (ChO) and a bi-enzyme of ChO and horseradish peroxidase (HRP) onto multi-wall carbon nanotubes (MWCNT) modified glassy carbon (GC) electrodes. These choline biosensors were fabricated by immobilization of enzymes on the negatively charged MWCNT surface through alternatively assembling a cationic polydiallydiimethylammonium chloride (PDDA) layer and an enzyme layer. Using this layer-by-layer assembling approach, bioactive nanocomposite film of a PDDA/ChO/PDDA/HRP/PDDA/CNT (ChO/HRP/CNT) and a PDDA/ChO/PDDA/ CNT (ChO/ CNT) were fabricated on GC surface, respectively. Owning to the electrocatalytic effect of carbon nanotubes, themore » measurement of faradic responses resulting from enzymatic reactions has been realized at low potential with acceptable sensitivity. It is found the ChO/HRP/CNT biosensor is more sensitive than the ChO/CNT one. Experimental parameters affecting the sensitivity of biosensors, e.g. applied potential, flow rate, etc. were optimized and potential interference was examined. The response time for this choline biosensor is fast (less than a few seconds). The linear range of detection for the choline biosensor is from 5 x 10-5 to 5 x 10-3 M and the detection limit is determined to be about 1.0 x 10-5 M.« less

Electrochemical evidence that pyranopterin redox chemistry controls the catalysis of YedY, a mononuclear Mo enzyme

PubMed Central

Adamson, Hope; Simonov, Alexandr N.; Kierzek, Michelina; Rothery, Richard A.; Weiner, Joel H.; Bond, Alan M.

2015-01-01

A long-standing contradiction in the field of mononuclear Mo enzyme research is that small-molecule chemistry on active-site mimic compounds predicts ligand participation in the electron transfer reactions, but biochemical measurements only suggest metal-centered catalytic electron transfer. With the simultaneous measurement of substrate turnover and reversible electron transfer that is provided by Fourier-transformed alternating-current voltammetry, we show that Escherichia coli YedY is a mononuclear Mo enzyme that reconciles this conflict. In YedY, addition of three protons and three electrons to the well-characterized “as-isolated” Mo(V) oxidation state is needed to initiate the catalytic reduction of either dimethyl sulfoxide or trimethylamine N-oxide. Based on comparison with earlier studies and our UV-vis redox titration data, we assign the reversible one-proton and one-electron reduction process centered around +174 mV vs. standard hydrogen electrode at pH 7 to a Mo(V)-to-Mo(IV) conversion but ascribe the two-proton and two-electron transition occurring at negative potential to the organic pyranopterin ligand system. We predict that a dihydro-to-tetrahydro transition is needed to generate the catalytically active state of the enzyme. This is a previously unidentified mechanism, suggested by the structural simplicity of YedY, a protein in which Mo is the only metal site. PMID:26561582

Glucose biosensor based on the immobilization of glucose oxidase on electrochemically synthesized polypyrrole-poly(vinyl sulphonate) composite film by cross-linking with glutaraldehyde.

PubMed

Colak, Ozlem; Yaşar, Ahmet; Cete, Servet; Arslan, Fatma

2012-10-01

In this study, a novel amperometric glucose biosensor was developed by immobilizing glucose oxidase (GOX) by cross-linking via glutaraldehyde on electrochemically polymerized polypyrrole-poly(vinyl sulphonate) (PPy-PVS) films on the surface of a platinum (Pt) electrode. Electropolymerization of pyrrole and poly(vinyl sulphonate) on the Pt surface was carried out with an electrochemical cell containing pyrrole and poly(vinyl sulphonate) by cyclic voltammetry between -1.0 and + 2.0 V (vs.Ag/AgCl) at a scan rate of 50 mV/s upon the Pt electrode. The amperometric determination was based on the electrochemical detection of H(2)O(2) generated in enzymatic reaction of glucose. Determination of glucose was carried out by the oxidation of enzymatically produced H(2)O(2) at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and optimum parameters were found to be 7.5 and 65°C, respectively. The effect of working potential was investigated and optimum potential was determined to be 0.4 V. The operational stability of the enzyme electrode was also studied. The response of the PPy/PVS-GOX glucose biosensor exhibited good reproducibility with a relative standard deviation (RSD) of 2.48%. The glucose biosensor retained 63% of initial activity after 93 days when stored in 0.1 M phosphate buffer solution of pH 7.5 at 4°C. With the low operating potential, the biosensor demonstrated little interference from the possible interferants.

A sensitive label-free electrochemical immunosensor for detection of cytokeratin 19 fragment antigen 21-1 based on 3D graphene with gold nanopaticle modified electrode.

PubMed

Zeng, Yan; Bao, Jing; Zhao, Yanan; Huo, Danqun; Chen, Mei; Yang, Mei; Fa, Huanbao; Hou, Changjun

2018-02-01

Previous studies have confirmed that cytokeratin 19 fragment antigen 21-1 (CYFRA 21-1) serves as a powerful biomarker in non-small cell lung cancer (NSCLC). Herein, we report for the first time a label-free electrochemical immunosensor for sensitive and selective detection of tumor marker CYFRA21-1. In this work, three-dimensional graphene @ gold nanoparticles (3D-G@Au) nanocomposite was modified on the glassy carbon electrode (GCE) surface to enhance the conductivity of immunosensor. The anti-CYFRA21-1 captured and fixed on the modified GCE through the cross-linking of chitosan (CS), glutaraldehyde (GA) and anti-CYFRA21-1. The differential pulse voltammetry (DPV) peak current change due to the specific interaction between anti-CYFRA21-1 and CYFRA21-1 on the modified electrode surface was utilized to detect CYFRA21-1. Under optimized conditions, the proposed electrochemical immunosensor was employed to detect CYFRA21-1 and exhibited a wide linear range of 0.25-800ngmL -1 and low detection limit of 100pgmL -1 (S/N = 3). Moreover, the recovery rates of serum samples were in the range from 95.2% to 108.7% and the developed immunosensor also shows a good correlation (less than 6.6%) with enzyme-linked immunosorbent assay (ELISA) in the detection of clinical serum samples. Therefore, it is expected that the proposed immunosensor based on a 3D-G@Au has great potential in clinical medical diagnosis of CYFRA21-1. Copyright © 2017 Elsevier B.V. All rights reserved.

Impacts | Hydrogen and Fuel Cells | NREL

Science.gov Websites

Impacts Impacts Read about NREL's impacts on innovations in hydrogen and fuel cell research and -Splitting Electrodes NREL Shows How Cyanobacteria Build Hydrogen-Producing Enzyme Fuel Cell Systems R&D -Speed Scanner to Monitor Fuel Cell Material Defects Making Fuel Cells Cleaner, Better, and Cheaper GM

[Progress on suxamethonium chloride analysis].

PubMed

Jiang, Ming-Zhe; Cheng, Xiang-Wei; Chu, Jian-Xin

2013-12-01

Abstract: Suxamethonium chloride is a depolarizing muscle relaxant used in general anesthesia. In overdose, it causes adverse reactions such as bradycardia, arrhythmia, cardiac arrest, and death. The article reviews the progress on testing methods of suxamethonium chloride such as infrared spectroscopy, chemical color reaction, chemical titration, enzyme electrode, chromatography and mass spectrometry.

Development of Microbial and Enzymatic Fuel Cells for Bio-Inspired Power Sources

DTIC Science & Technology

2009-03-01

that of the oxidation of NADH as possible.[30] A variety of organic mediators have been studied for the anode, including phenazines ,[38] dyes,[39,40...glucose-6-phosphate dehydrogenase on the rotating graphite disc electrode modified with phenazine methosulfate. Enzyme Microb. Technol. 1993, 15 (6), 525

Chitosan coated on the layers' glucose oxidase immobilized on cysteamine/Au electrode for use as glucose biosensor.

PubMed

Zhang, Yawen; Li, Yunqiu; Wu, Wenjian; Jiang, Yuren; Hu, Biru

2014-10-15

A glucose biosensor was developed via direct immobilization of glucose oxidase (GOD) by self-assembled cysteamine monolayer on Au electrode surface followed by coating chitosan on the surface of electrode. In this work, chitosan film was coated on the surface of GOD as a protection film to ensure the stability and biocompatibility of the constructed glucose biosensor. The different application ranges of sensors were fabricated by immobilizing varied layers of GOD. The modified surface film was characterized by a scanning electron microscope (SEM) and the fabrication process of the biosensor was confirmed through electrochemical impedance spectroscopy (EIS) of ferrocyanide. The performance of cyclic voltammetry (CV) in the absence and presence of 25 mM glucose and ferrocenemethanol showed a diffusion-controlled electrode process and reflected the different maximum currents between the different GOD layers. With the developed glucose biosensor, the detection limits of the two linear responses are 49.96 μM and 316.8 μM with the sensitivities of 8.91 μA mM(-1)cm(-2) and 2.93 μA mM(-1)cm(-2), respectively. In addition, good stability (up to 30 days) of the developed biosensor was observed. The advantages of this new method for sensors construction was convenient and different width ranges of detection can be obtained by modified varied layers of GOD. The sensor with two layers of enzyme displayed two current linear responses of glucose. The present work provided a simplicity and novelty method for producing biosensors, which may help design enzyme reactors and biosensors in the future. Copyright © 2014 Elsevier B.V. All rights reserved.

Direct and mediated electrochemistry of peroxidase and its electrocatalysis on a variety of screen-printed carbon electrodes: amperometric hydrogen peroxide and phenols biosensor.

PubMed

Chekin, Fereshteh; Gorton, Lo; Tapsobea, Issa

2015-01-01

This study compares the behaviour of direct and mediated electrochemistry of horseradish peroxidase (HRP) immobilised on screen-printed carbon electrodes (SPCEs), screen-printed carbon electrodes modified with carboxyl-functionalised multi-wall carbon nanotubes (MWCNT-SPCEs) and screen-printed carbon electrodes modified with carboxyl-functionalised single-wall carbon nanotubes (SWCNT-SPCEs). The techniques of cyclic voltammetry and amperometry in the flow mode were used to characterise the properties of the HRP immobilised on screen-printed electrodes. From measurements of the mediated and mediatorless currents of hydrogen peroxide reduction at the HRP-modified electrodes, it was concluded that the fraction of enzyme molecules in direct electron transfer (DET) contact with the electrode varies substantially for the different electrodes. It was observed that the screen-printed carbon electrodes modified with carbon nanotubes (MWCNT-SPCEs and SWCNT-SPCEs) demonstrated a substantially higher percentage (≈100 %) of HRP molecules in DET contact than the screen-printed carbon electrodes (≈60 %). The HRP-modified electrodes were used for determination of hydrogen peroxide in mediatorless mode. The SWCNT-SPCE gave the lowest detection limit (0.40 ± 0.09 μM) followed by MWCNT-SPCE (0.48 ± 0.07 μM) and SPCE (0.98 ± 0.2 μM). These modified electrodes were additionally developed for amperometric determination of phenolic compounds. It was found that the SWCNT-SPCE gave a detection limit for catechol of 110.2 ± 3.6 nM, dopamine of 640.2 ± 9.2 nM, octopamine of 3341 ± 15 nM, pyrogallol of 50.10 ± 2.9 nM and 3,4-dihydroxy-L-phenylalanine of 980.7 ± 8.7 nM using 50 μM H2O2 in the flow carrier.

Conductometric Microbiosensors for Environmental Monitoring

PubMed Central

Jaffrezic-Renault, Nicole; Dzyadevych, Sergei V.

2008-01-01

This review presents the principles of conductometric measurements in ionic media and the equivalent electrical circuits of different designs for conductometric measurements. These types of measurements were first applied for monitoring biocatalytic reactions. The use of conductometric microtransducers is then presented and detailed in the case of pollutant detection for environmental monitoring. Conductometric biosensors have advantages over other types of transducers: they can be produced through inexpensive thin- film standard technology, no reference electrode is needed and differential mode measurements allow cancellation of a lot of interferences. The specifications obtained for the detection of different pesticides, herbicides and heavy metal ions, based on enzyme inhibition, are presented as well as those obtained for the detection of formaldehyde, 4- chlorophenol, nitrate and proteins as markers of dissolved organic carbon based on enzymatic microbiosensors. PMID:27879836

Electrochemical Sunset Yellow Biosensor Based on Photocured Polyacrylamide Membrane for Food Dye Monitoring

PubMed Central

Rozi, Normazida; Ahmad, Amalina; Yook Heng, Lee; Shyuan, Loh Kee; Hanifah, Sharina Abu

2018-01-01

An enzyme-based electrochemical biosensor was investigated for the analysis of Sunset Yellow synthetic food dye. A glassy carbon electrode was coated with a poly(acrylamide-co-ethyl methacrylate) membrane to immobilize laccase using a single-step photopolymerization procedure. Poly(acrylamide-co-ethyl methacrylate) membrane was demonstrated to have acceptable water absorption and suitable for biosensor application. Sunset Yellow biosensor exhibited a linear response range from 0.08 to 10.00 µM with a detection limit of 0.02 µM. This biosensor was successfully used to determine Sunset Yellow in soft drinks with recoveries of 99.0–101.6%. The method was validated using high-performance liquid chromatography, indicating the biosensor can be as a promising alternative method for Sunset Yellow detection. PMID:29301262

Integrated electrochemical gluconic acid biosensor based on self-assembled monolayer-modified gold electrodes. Application to the analysis of gluconic acid in musts and wines.

PubMed

Campuzano, S; Gamella, M; Serra, B; Reviejo, A J; Pingarrón, J M

2007-03-21

An integrated amperometric gluconic acid biosensor constructed using a gold electrode (AuE) modified with a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA) on which gluconate dehydrogenase (GADH, 0.84 U) and the mediator tetrathiafulvalene (TTF, 1.5 micromol) were coimmobilized by covering the electrode surface with a dialysis membrane is reported. The working conditions selected were Eapp=+0.15 V and 25+/-1 degrees C. The useful lifetime of one single TTF-GADH-MPA-AuE was surprisingly long. After 53 days of continuous use, the biosensor exhibited 86% of the original sensitivity. A linear calibration plot was obtained for gluconic acid over the 6.0x10(-7) to 2.0x10(-5) M concentration range, with a limit of detection of 1.9x10(-7) M. The effect of potential interferents (glucose, fructose, galactose, arabinose, and tartaric, citric, malic, ascorbic, gallic, and caffeic acids) on the biosensor response was evaluated. The behavior of the biosensor in a flow-injection system in connection with amperometric detection was tested. The analytical usefulness of the biosensor was evaluated by determining gluconic acid in wine and must samples, and the results obtained were validated by comparison with those provided by using a commercial enzyme test kit.

Designing electrochemical interfaces with functionalized magnetic nanoparticles and wrapped carbon nanotubes as platforms for the construction of high-performance bienzyme biosensors.

PubMed

Eguílaz, Marcos; Villalonga, Reynaldo; Yáñez-Sedeño, Paloma; Pingarrón, José M

2011-10-15

The design of a novel biosensing electrode surface, combining the advantages of magnetic ferrite nanoparticles (MNPs) functionalized with glutaraldehyde (GA) and poly(diallyldimethylammonium chloride) (PDDA)-coated multiwalled carbon nanotubes (MWCNTs) as platforms for the construction of high-performance multienzyme biosensors, is reported in this work. Before the immobilization of enzymes, GA-MNP/PDDA/MWCNT composites were prepared by wrapping of carboxylated MWCNTs with positively charged PDDA and interaction with GA-functionalized MNPs. The nanoconjugates were characterized by scanning electron microscopy (SEM) and electrochemistry. The electrode platform was used to construct a bienzyme biosensor for the determination of cholesterol, which implied coimmobilization of cholesterol oxidase (ChOx) and peroxidase (HRP) and the use of hydroquinone as redox mediator. Optimization of all variables involved in the preparation and analytical performance of the bienzyme electrode was accomplished. At an applied potential of -0.05 V, a linear calibration graph for cholesterol was obtained in the 0.01-0.95 mM concentration range. The detection limit (0.85 μM), the apparent Michaelis-Menten constant (1.57 mM), the stability of the biosensor, and the calculated activation energy can be advantageously compared with the analytical characteristics of other CNT-based cholesterol biosensors reported in the literature. Analysis of human serum spiked with cholesterol at different concentration levels yielded recoveries between 100% and 103% © 2011 American Chemical Society

Enzyme-less electrochemical displacement heterogeneous immunosensor for diclofenac detection.

PubMed

Nguyen, T T K; Vu, T T; Anquetin, G; Tran, H V; Reisberg, S; Noël, V; Mattana, G; Nguyen, Q V; Dai Lam, Tran; Pham, M C; Piro, B

2017-11-15

We describe an electrochemical immunosensor based on functionalization of a working electrode by electrografting two functional diazonium salts. The first one is a molecular probe, diclofenac, coupled with an arylamine onto which a specific antibody is immobilized by affinity interactions; the second is a redox probe (a quinone) also coupled with an arylamine, able to transduce the hapten-antibody association into a change in electroactivity. The steric hindrance induced by the antibody leads to a current decrease upon binding of the antibody on the grafted molecular probe; conversely, when diclofenac is present in solution, a displacement equilibrium occurs between the target diffusing into the solution and the grafted probe. This leads to dissociation of the antibody from the electrode surface, event which is transduced into a current increase ("signal-on" detection). The detection limit is ca. 20 fM, corresponding to 6pgL -1 diclofenac, which is competitive compared to other label-free immunosensors. We demonstrate that the sensor is selective and is able to quantify diclofenac in tap water. Copyright © 2017 Elsevier B.V. All rights reserved.

Supercapacitors based on modified graphene electrodes with poly(ionic liquid)

NASA Astrophysics Data System (ADS)

Trigueiro, João Paulo C.; Lavall, Rodrigo L.; Silva, Glaura G.

2014-06-01

The improved accessibility of the electrolyte to the surface of carbon nanomaterials is a challenge to be overcome in supercapacitors based on ionic liquid electrolytes. In this study, we report the preparation of supercapacitors based on reduced graphene oxide (RGO) electrodes and ionic liquid as the electrolyte (specifically, 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide or [MPPy][TFSI]). Two types of electrodes were compared: the RGO-based electrode and a poly(ionic liquid)-modified RGO electrode (PIL:RGO). The supercapacitor produced with the PIL:RGO electrode and [MPPy][TFSI] showed an electrochemical stability of 3 V and provided a capacitance of 71.5 F g-1 at room temperature; this capacitance is 130% higher with respect to the RGO-based supercapacitor. The decrease of the specific capacitance after 2000 cycles is only 10% for the PIL:RGO-based device. The results revealed the potential of the PIL:RGO material as an electrode for supercapacitors. This composite electrode increases the compatibility with the ionic liquid electrolyte compared to an RGO electrode, promoting an increase in the effective surface area of the electrode accessible to the electrolyte ions.

Natural polyhydroxyalkanoate-gold nanocomposite based biosensor for detection of antimalarial drug artemisinin.

PubMed

Phukon, Pinkee; Radhapyari, Keisham; Konwar, Bolin Kumar; Khan, Raju

2014-04-01

The worrisome trend of antimalarial resistance has already highlighted the importance of artemisinin as a potent antimalarial agent. The current investigation aimed at fabricating a biosensor based on natural polymer polyhydroxyalkanoate-gold nanoparticle composite mounting on an indium-tin oxide glass plate for the analysis of artemisinin. The biosensor was fabricated using an adsorbing horse-radish peroxidase enzyme on the electrode surface for which cyclic voltammetry was used to monitor the electro-catalytic reduction of artemisinin under diffusion controlled conditions. Electrochemical interfacial properties and immobilization of enzyme onto a polyhydroxyalkanoate-gold nanoparticle film were evaluated, and confirmed by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The differential pulse voltammetric peak current for artemisinin was increased linearly (concentration range of 0.01-0.08μg mL(-1)) with sensitivity of 0.26μAμg mL(-1). The greater sensitivity of the fabricated biosensor to artemisinin (optimum limits of detection were 0.0035μg mL(-1) and 0.0036μg mL(-1) in bulk and spiked human serum, respectively) could be of much aid in medical diagnosis. Copyright © 2014 Elsevier B.V. All rights reserved.

A novel amperometric biosensor based on gold nanoparticles anchored on reduced graphene oxide for sensitive detection of l-lactate tumor biomarker.

PubMed

Azzouzi, Sawsen; Rotariu, Lucian; Benito, Ana M; Maser, Wolfgang K; Ben Ali, Mounir; Bala, Camelia

2015-07-15

In this work, a novel amperometric biosensor based on gold nanoparticles anchored on reduced graphene oxide (RGO-AuNPs) and l-lactate dehydrogenase (LDH) was developed for the sensing of l-lactate. Firstly, the RGO-AuNPs modified screen printed electrodes were tested for NADH detection showing a wide dynamic range and a low detection limit. Next, the biosensor was constructed by incorporating both enzyme and RGO-AuNPs in a sol gel matrix derived from tetrametoxysilane and methyltrimetoxysilane. The enzyme loading, working pH, and coenzyme concentration were optimized. The biosensor linearly responded to l-lactate in the range of 10µM-5mM and showed a good specific sensitivity of 154µA/mMcm(2) with a detection limit of 0.13µM. This was accompanied by good reproducibility and operational stability. Tests on artificial serum proved that l-lactate can be determined practically without interferences from commonly interfering compounds such as urate, paracetamol and l-ascorbate. Our LDH/RGO-AuNPs/SPCE based biosensor thus performs as electrochemical device for the detection of l-lactate as a viable early cancer bio-marker. Copyright © 2015 Elsevier B.V. All rights reserved.

Hierarchical CNFs/MnCo2O4.5 nanofibers as a highly active oxidase mimetic and its application in biosensing

NASA Astrophysics Data System (ADS)

Gao, Mu; Lu, Xiaofeng; Nie, Guangdi; Chi, Maoqiang; Wang, Ce

2017-12-01

Recently, much attention has been paid on the nanomaterial-based artificial enzymes due to their tunable catalytic activity, high stability and low cost compared to the natural enzymes. Different from the peroxidase mimics which have been studied for several decades, nanomaterials with oxidase-like property are burgeoning in the recent years. In this paper, hierarchical carbon nanofibers (CNFs)/MnCo2O4.5 nanofibers as efficient oxidase mimics are reported. The products are synthesized by an electrospinning technique and an electrochemcial deposition process in which the CNFs are used as the working electrode where MnCo2O4.5 nanosheets deposit on. The resulting binary metal oxide-based nanocomposites exhibit a good oxidase-like activity toward the oxidations of 3,3‧,5,5‧tetramethylbenzi-dine (TMB), 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) salt and o-phenylenediamine (OPD) without exogenous addition of H2O2. The system of CNFs/MnCo2O4.5-TMB can be used as a candidate to detect sulfite and ascorbic acid via a colorimetric method with a high sensitivity. This work provides the efficient utilization and potential applications of binary metal oxide-based nanocomposites with oxidase activities in biosensors and other biotechnologies.

Electrolytic treatment of colorectal liver tumour deposits in a rat model: a technique with potential for patients with unresectable liver tumours.

PubMed

Wemyss-Holden, S A; Robertson, G S; Hall, P D; Dennison, A R; Maddern, G J

2000-01-01

Patients with unresectable malignant liver tumours have a poor prognosis. A technique is needed which improves long-term survival. Previous studies in the rat have shown that electrolysis is a safe, predictable and reproducible method for creating areas of necrosis in the normal rat liver. This study examined the effects of electrolysis on colorectal liver 'metastases' in the rat. Tumours of colorectal origin were implanted into the livers of Wistar-WAG rats. Two weeks after implantation the tumours were treated with electrolysis. A direct current generator, connected to 2 platinum intrahepatic electrodes was used to examine the effects of various electrode configurations on the extent of tumour necrosis. Significant (p<0.001) tumour ablation was achieved with all electrode configurations. Tumour necrosis was more complete (p<0.05) with the electrodes positioned on either side of the tumour than with both electrodes placed in the centre of the tumour. Liver enzymes (AST and ALT) were significantly (p<0.001) elevated after treatment, but returned towards normal by 2 days. This study has shown that colorectal liver 'metastasis' can be ablated by electrolysis in a rat model. Two separate mechanisms of tumour ablation were observed: With the electrodes directly in or adjacent to the tumour, necrosis resulted from the action of cytotoxic electrode products, whereas by positioning the electrodes proximal to the tumour, necrosis was induced by a 'secondary' ischaemic effect. The findings confirm the view that electrolysis has great potential for treating patients with unresectable malignant liver tumours.

Cellobiose Dehydrogenase Aryl Diazonium Modified Single Walled Carbon Nanotubes: Enhanced Direct Electron Transfer through a Positively Charged Surface

PubMed Central

2011-01-01

One of the challenges in the field of biosensors and biofuel cells is to establish a highly efficient electron transfer rate between the active site of redox enzymes and electrodes to fully access the catalytic potential of the biocatalyst and achieve high current densities. We report on very efficient direct electron transfer (DET) between cellobiose dehydrogenase (CDH) from Phanerochaete sordida (PsCDH) and surface modified single walled carbon nanotubes (SWCNT). Sonicated SWCNTs were adsorbed on the top of glassy carbon electrodes and modified with aryl diazonium salts generated in situ from p-aminobenzoic acid and p-phenylenediamine, thus featuring at acidic pH (3.5 and 4.5) negative or positive surface charges. After adsorption of PsCDH, both electrode types showed excellent long-term stability and very efficient DET. The modified electrode presenting p-aminophenyl groups produced a DET current density of 500 μA cm−2 at 200 mV vs normal hydrogen reference electrode (NHE) in a 5 mM lactose solution buffered at pH 3.5. This is the highest reported DET value so far using a CDH modified electrode and comes close to electrodes using mediated electron transfer. Moreover, the onset of the electrocatalytic current for lactose oxidation started at 70 mV vs NHE, a potential which is 50 mV lower compared to when unmodified SWCNTs were used. This effect potentially reduces the interference by oxidizable matrix components in biosensors and increases the open circuit potential in biofuel cells. The stability of the electrode was greatly increased compared with unmodified but cross-linked SWCNTs electrodes and lost only 15% of the initial current after 50 h of constant potential scanning. PMID:21417322

Cellobiose dehydrogenase aryl diazonium modified single walled carbon nanotubes: enhanced direct electron transfer through a positively charged surface.

PubMed

Tasca, Federico; Harreither, Wolfgang; Ludwig, Roland; Gooding, John Justin; Gorton, Lo

2011-04-15

One of the challenges in the field of biosensors and biofuel cells is to establish a highly efficient electron transfer rate between the active site of redox enzymes and electrodes to fully access the catalytic potential of the biocatalyst and achieve high current densities. We report on very efficient direct electron transfer (DET) between cellobiose dehydrogenase (CDH) from Phanerochaete sordida (PsCDH) and surface modified single walled carbon nanotubes (SWCNT). Sonicated SWCNTs were adsorbed on the top of glassy carbon electrodes and modified with aryl diazonium salts generated in situ from p-aminobenzoic acid and p-phenylenediamine, thus featuring at acidic pH (3.5 and 4.5) negative or positive surface charges. After adsorption of PsCDH, both electrode types showed excellent long-term stability and very efficient DET. The modified electrode presenting p-aminophenyl groups produced a DET current density of 500 μA cm(-2) at 200 mV vs normal hydrogen reference electrode (NHE) in a 5 mM lactose solution buffered at pH 3.5. This is the highest reported DET value so far using a CDH modified electrode and comes close to electrodes using mediated electron transfer. Moreover, the onset of the electrocatalytic current for lactose oxidation started at 70 mV vs NHE, a potential which is 50 mV lower compared to when unmodified SWCNTs were used. This effect potentially reduces the interference by oxidizable matrix components in biosensors and increases the open circuit potential in biofuel cells. The stability of the electrode was greatly increased compared with unmodified but cross-linked SWCNTs electrodes and lost only 15% of the initial current after 50 h of constant potential scanning. © 2011 American Chemical Society

Development and characterization of a FIA system for selective assay of L-ascorbic acid in food samples.

PubMed

Vig, Attila; Igloi, Attila; Adanyi, Nora; Gyemant, Gyongyi; Csutoras, Csaba; Kiss, Attila

2010-10-01

An amperometric detector and an enzymatic reaction were combined for the measurement of L-ascorbic acid. The enzyme cell (containing immobilized ascorbate oxidase) was connected to a flow injection analyzer (FIA) system with a glassy carbon electrode as an amperometric detector. During optimization and measurements two sample injectors were used, one before and one after the enzyme cell, thus eliminating the background interferences. Subtraction of the signal area given in the presence of enzyme from the one given in the absence of enzyme was applied for measuring analyte concentrations and calibration at 400 mV. Analysis capacity of system is 25 samples/hour. The relative standard deviation (RSD) was below 5% (5 times repeated, 400 μmol/L conc.), linearity up to 400 μmol/L, limit of detection (LOD) 5 μmol/L, fitting of calibration curve in 25-400 μmol/L range was R (2) = 0.99.

Printable organic thin film transistors for glucose detection incorporating inkjet-printing of the enzyme recognition element

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elkington, D., E-mail: Daniel.Elkington@newcastle.edu.au; Wasson, M.; Belcher, W.

The effect of device architecture upon the response of printable enzymatic glucose sensors based on poly(3-hexythiophene) (P3HT) organic thin film transistors is presented. The change in drain current is used as the basis for glucose detection and we show that significant improvements in drain current response time can be achieved by modifying the design of the sensor structure. In particular, we show that eliminating the dielectric layer and reducing the thickness of the active layer reduce the device response time considerably. The results are in good agreement with a diffusion based model of device operation, where an initial rapid dedopingmore » process is followed by a slower doping of the P3HT layer from protons that are enzymatically generated by glucose oxidase (GOX) at the Nafion gate electrode. The fitted diffusion data are consistent with a P3HT doping region that is close to the source-drain electrodes rather than located at the P3HT:[Nafion:GOX] interface. Finally, we demonstrate that further improvements in sensor structure and morphology can be achieved by inkjet-printing the GOX layer, offering a pathway to low-cost printed biosensors for the detection of glucose in saliva.« less

Membrane-based electrochemical nanobiosensor for Escherichia coli detection and analysis of cells viability.

PubMed

Cheng, Ming Soon; Lau, Suk Hiang; Chow, Vincent T; Toh, Chee-Seng

2011-08-01

A sensitive and selective membrane-based electrochemical nanobiosensor is developed for specific quantitative label-free detection of Escherichia coli (E. coli) cells and analysis of viable but nonculturable (VBNC) E. coli cells which remain mostly undetected using current methods. The sensing mechanism relies on the blocking of nanochannels of a nanoporous alumina-membrane modified electrode, upon the formation of immune complexes at the nanoporous membrane. The resulting obstacle to diffusive mass transfer of a redox probe in the analysis solution to the underlying platinum electrode reduces the Faradaic signal response of the biosensor, measured using cyclic voltammetry. Antibody loading under conditions of varying antibody concentrations and pHs are optimized. The biosensor gives a low detection limit of 22 cfu mL(-1) (R(2) = 0.999) over a wide linear working range of 10 to 10(6) cfu mL(-1). It is specific toward E. coli with minimal cross-reactivity to two other pathogenic bacteria (commonly found in waters). Relative standard deviation (RSD) for triplicate measurements of 2.5% indicates reasonably useful level of reproducibility. Differentiation of live, VBNC, and dead cells are carried out after the cell capture and quantitation step, by simple monitoring of the cells' enzyme activity using the same redox probe in the analysis solution, in the presence of glucose.

Multi-enzyme complexes on DNA scaffolds capable of substrate channelling with an artificial swinging arm

NASA Astrophysics Data System (ADS)

Fu, Jinglin; Yang, Yuhe Renee; Johnson-Buck, Alexander; Liu, Minghui; Liu, Yan; Walter, Nils G.; Woodbury, Neal W.; Yan, Hao

2014-07-01

Swinging arms are a key functional component of multistep catalytic transformations in many naturally occurring multi-enzyme complexes. This arm is typically a prosthetic chemical group that is covalently attached to the enzyme complex via a flexible linker, allowing the direct transfer of substrate molecules between multiple active sites within the complex. Mimicking this method of substrate channelling outside the cellular environment requires precise control over the spatial parameters of the individual components within the assembled complex. DNA nanostructures can be used to organize functional molecules with nanoscale precision and can also provide nanomechanical control. Until now, protein-DNA assemblies have been used to organize cascades of enzymatic reactions by controlling the relative distance and orientation of enzymatic components or by facilitating the interface between enzymes/cofactors and electrode surfaces. Here, we show that a DNA nanostructure can be used to create a multi-enzyme complex in which an artificial swinging arm facilitates hydride transfer between two coupled dehydrogenases. By exploiting the programmability of DNA nanostructures, key parameters including position, stoichiometry and inter-enzyme distance can be manipulated for optimal activity.

Multi-enzyme complexes on DNA scaffolds capable of substrate channelling with an artificial swinging arm.

PubMed

Fu, Jinglin; Yang, Yuhe Renee; Johnson-Buck, Alexander; Liu, Minghui; Liu, Yan; Walter, Nils G; Woodbury, Neal W; Yan, Hao

2014-07-01

Swinging arms are a key functional component of multistep catalytic transformations in many naturally occurring multi-enzyme complexes. This arm is typically a prosthetic chemical group that is covalently attached to the enzyme complex via a flexible linker, allowing the direct transfer of substrate molecules between multiple active sites within the complex. Mimicking this method of substrate channelling outside the cellular environment requires precise control over the spatial parameters of the individual components within the assembled complex. DNA nanostructures can be used to organize functional molecules with nanoscale precision and can also provide nanomechanical control. Until now, protein-DNA assemblies have been used to organize cascades of enzymatic reactions by controlling the relative distance and orientation of enzymatic components or by facilitating the interface between enzymes/cofactors and electrode surfaces. Here, we show that a DNA nanostructure can be used to create a multi-enzyme complex in which an artificial swinging arm facilitates hydride transfer between two coupled dehydrogenases. By exploiting the programmability of DNA nanostructures, key parameters including position, stoichiometry and inter-enzyme distance can be manipulated for optimal activity.

Recent advances in the development and application of nanoelectrodes.

PubMed

Fan, Yunshan; Han, Chu; Zhang, Bo

2016-10-07

Nanoelectrodes have key advantages compared to electrodes of conventional size and are the tool of choice for numerous applications in both fundamental electrochemistry research and bioelectrochemical analysis. This Minireview summarizes recent advances in the development, characterization, and use of nanoelectrodes in nanoscale electroanalytical chemistry. Methods of nanoelectrode preparation include laser-pulled glass-sealed metal nanoelectrodes, mass-produced nanoelectrodes, carbon nanotube based and carbon-filled nanopipettes, and tunneling nanoelectrodes. Several new topics of their recent application are covered, which include the use of nanoelectrodes for electrochemical imaging at ultrahigh spatial resolution, imaging with nanoelectrodes and nanopipettes, electrochemical analysis of single cells, single enzymes, and single nanoparticles, and the use of nanoelectrodes to understand single nanobubbles.

Detection of basal acetylcholine release in the microdialysis of rat frontal cortex by high-performance liquid chromatography using a horseradish peroxidase-osmium redox polymer electrode with pre-enzyme reactor.

PubMed

Kato, T; Liu, J K; Yamamoto, K; Osborne, P G; Niwa, O

1996-06-28

To determine the basal acetylcholine level in the dialysate of rat frontal cortex, a horseradish peroxidase-osmium redox polymer-modified glassy carbon electrode (HRP-GCE) was employed instead of the conventional platinum electrode used in high-performance liquid chromatography-electrochemical detection (HPLC-ED). In initial experiments, an oxidizable unknown compound interfered with the detection of basal acetylcholine release on HPLC-HRP-GCE. An immobilized peroxidase-choline oxidase precolumn (pre-reactor) was included in the HPLC system, to eliminate the interference from the unknown compound. This combination could detect less than 10 fmol of standard acetylcholine and basal acetylcholine levels in the dialysate from a conventional concentric design microdialysis probe, without the use of cholinesterase inhibitor, and may facilitate physiological investigation of cholinergic neuronal activity in the central nervous system.

Fabrication of Graphene on Kevlar Supercapacitor Electrodes

DTIC Science & Technology

2011-05-01

fabricated with graphene to investigate its applicability for energy storage devices, as this carbon- based material has a large surface area and...Distribution List 14 iv List of Figures Figure 1. Dip-and-dry technique applied to Kevlar- based electrodes...2  Figure 2. Three-electrode system used for the CV measurements. The (1) working electrode was the Kevlar- based electrode; (2) the counter

Determination of total creatine kinase activity in blood serum using an amperometric biosensor based on glucose oxidase and hexokinase.

PubMed

Kucherenko, I S; Soldatkin, O O; Lagarde, F; Jaffrezic-Renault, N; Dzyadevych, S V; Soldatkin, A P

2015-11-01

Creatine kinase (CK: adenosine-5-triphosphate-creatine phosphotransferase) is an important enzyme of muscle cells; the presence of a large amount of the enzyme in blood serum is a biomarker of muscular injuries, such as acute myocardial infarction. This work describes a bi-enzyme (glucose oxidase and hexokinase based) biosensor for rapid and convenient determination of CK activity by measuring the rate of ATP production by this enzyme. Simultaneously the biosensor determines glucose concentration in the sample. Platinum disk electrodes were used as amperometric transducers. Glucose oxidase and hexokinase were co-immobilized via cross-linking with BSA by glutaraldehyde and served as a biorecognition element of the biosensor. The biosensor work at different concentrations of CK substrates (ADP and creatine phosphate) was investigated; optimal concentration of ADP was 1mM, and creatine phosphate - 10 mM. The reproducibility of the biosensor responses to glucose, ATP and CK during a day was tested (relative standard deviation of 15 responses to glucose was 2%, to ATP - 6%, to CK - 7-18% depending on concentration of the CK). Total time of CK analysis was 10 min. The measurements of creatine kinase in blood serum samples were carried out (at 20-fold sample dilution). Twentyfold dilution of serum samples was chosen as optimal for CK determination. The biosensor could distinguish healthy and ill people and evaluate the level of CK increase. Thus, the biosensor can be used as a test-system for CK analysis in blood serum or serve as a component of multibiosensors for determination of important blood substances. Determination of activity of other kinases by the developed biosensor is also possible for research purposes. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of annealing over optoelectronic properties of graphene based transparent electrodes

NASA Astrophysics Data System (ADS)

Yadav, Shriniwas; Kaur, Inderpreet

2016-04-01

Graphene, an atom-thick two dimensional graphitic material have led various fundamental breakthroughs in the field of science and technology. Due to their exceptional optical, physical and electrical properties, graphene based transparent electrodes have shown several applications in organic light emitting diodes, solar cells and thin film transistors. Here, we are presenting effect of annealing over optoelectronic properties of graphene based transparent electrodes. Graphene based transparent electrodes have been prepared by wet chemical approach over glass substrates. After fabrication, these electrodes tested for optical transmittance in visible region. Sheet resistance was measured using four probe method. Effect of thermal annealing at 200 °C was studied over optical and electrical performance of these electrodes. Optoelectronic performance was judged from ratio of direct current conductivity to optical conductivity (σdc/σopt) as a figure of merit for transparent conductors. The fabricated electrodes display good optical and electrical properties. Such electrodes can be alternatives for doped metal oxide based transparent electrodes.

Wireless enzyme sensor system for real-time monitoring of blood glucose levels in fish.

PubMed

Endo, Hideaki; Yonemori, Yuki; Hibi, Kyoko; Ren, Huifeng; Hayashi, Tetsuhito; Tsugawa, Wakako; Sode, Koji

2009-01-01

Periodic checks of fish health and the rapid detection of abnormalities are thus necessary at fish farms. Several studies indicate that blood glucose levels closely correlate to stress levels in fish and represent the state of respiratory or nutritional disturbance. We prepared a wireless enzyme sensor system to determine blood glucose levels in fish. It can be rapidly and conveniently monitored using the newly developed needle-type enzyme sensor, consisting of a Pt-Ir wire, Ag/AgCl paste, and glucose oxidase. To prevent the effects of interfering anionic species, such as uric acid and ascorbic acid, on the sensor response, the Pt-Ir electrode was coated with Nafion, and then glucose oxidase was immobilized on the coated electrode. The calibration curve of the glucose concentration was linear, from 0.18 to 144mg/dl, and the detection limit was 0.18mg/dl. The sensor was used to wirelessly monitor fish glucose levels. The sensor-calibrated glucose levels and actual blood glucose levels were in excellent agreement. The fluid of the inner sclera of the fish eyeball (EISF) was a suitable site for sensor implantation to obtain glucose sample. There was a close correlation between glucose concentrations in the EISF and those in the blood. Glucose concentrations in fish blood could be monitored in free-swimming fish in an aquarium for 3 days.

Use of epoxy-embedded electrodes to integrate electrochemical detection with microchip-based analysis systems.

PubMed

Selimovic, Asmira; Johnson, Alicia S; Kiss, István Z; Martin, R Scott

2011-04-01

A new method of fabricating electrodes for microchip devices that involves the use of Teflon molds and a commercially available epoxy to embed electrodes of various sizes and compositions is described. The resulting epoxy base can be polished to generate a fresh electrode and sealed against poly(dimethylsiloxane) (PDMS)-based fluidic structures. Microchip-based flow injection analysis was used to characterize the epoxy-embedded electrodes. It was shown that gold electrodes can be amalgamated with liquid mercury and the resulting mercury/gold electrode is used to selectively detect glutathione from lysed red blood cells. The ability to encapsulate multiple electrode materials of differing compositions enabled the integration of microchip electrophoresis with electrochemical detection. Finally, a unique feature of this approach is that the electrode connection is made from the bottom of the epoxy base. This enables the creation of three-dimensional gold pillar electrodes (65 μm in diameter and 27 μm in height) that can be integrated within a fluidic network. As compared with the use of a flat electrode of a similar diameter, the use of the pillar electrode led to improvements in both the sensitivity (72.1 pA/μM for the pillar versus 4.2 pA/μM for the flat electrode) and limit of detection (20 nM for the pillar versus 600 nM for the flat electrode), with catechol being the test analyte. These epoxy-embedded electrodes hold promise for the creation of inexpensive microfluidic devices that can be used to electrochemically detect biologically important analytes in a manner where the electrodes can be polished and a fresh electrode surface is generated as desired. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance and microbial community analysis of bio-electrocoagulation on simultaneous nitrification and denitrification in submerged membrane bioreactor at limited dissolved oxygen.

PubMed

Li, Liang; Dong, Yihua; Qian, Guangsheng; Hu, Xiaomin; Ye, Linlin

2018-06-01

A pair of Fe-C electrodes was installed in a traditional submerged membrane bioreactor (MBR, Rc), and a novel asynchronous periodic reversal bio-electrocoagulation system (Re) was developed. The simultaneous nitrification and denitrification (SND) performance was discussed under limited dissolved oxygen (DO). Results showed that electrocoagulation enhanced total nitrogen (TN) removal from 59.48% to 75.09% at 1.2 mg/L DO. Additionally, Fe electrode could increase sludge concentration, particle size, and enzyme activities related to nitrogen removal. The enzyme activities of Hydroxylamine oxidoreductase (HAO), Nitrate Reductase (NAR), nitric oxide reductase NOR and nitrous oxide reductase (N 2 OR) in Re were 38.35%, 21.59%, 89.96% and 38.64% higher than Rc, respectively. Moreover, electrocoagulation was advantageous for nitrite accumulation, indicating partial nitrification and denitrification were more easily achieved in Re. Besides, results from high throughput sequencing analysis revealed that electrocoagulation increased the relative abundance of most genera related to nitrogen removal, including Nitrosomonas, Comamonadaceae_unclassified, Haliangium and Denitratisoma. Copyright © 2018 Elsevier Ltd. All rights reserved.

MWCNT-ruthenium oxide composite paste electrode as non-enzymatic glucose sensor.

PubMed

Tehrani, Ramin M A; Ab Ghani, Sulaiman

2012-01-01

A non-enzymatic glucose sensor of multi-walled carbon nanotube-ruthenium oxide/composite paste electrode (MWCNT-RuO(2)/CPE) was developed. The electrode was characterized by using XRD, SEM, TEM and EIS. Meanwhile, cyclic voltammetry and amperometry were used to check on the performances of the MWCNT-RuO(2)/CPE towards glucose. The proposed electrode has displayed a synergistic effect of RuO(2) and MWCNT on the electrocatalytic oxidation of glucose in 3M NaOH. This was possible via the formation of transitions of two redox pairs, viz. Ru(VI)/Ru(IV) and Ru(VII)/Ru(VI). A linear range of 0.5-50mM glucose and a limit of detection of 33 μM glucose (S/N=3) were observed. There was no significant interference observable from the traditional interferences, viz. ascorbic acid and uric acid. Indeed, results so obtained have indicated that the developed MWCNT-RuO(2)/CPE would pave the way for a better future to glucose sensor development as its fabrication was without the use of any enzyme. Copyright © 2012 Elsevier B.V. All rights reserved.

Direct electrodeposition of porous gold nanowire arrays for biosensing applications.

PubMed

Zhang, Xinyi; Li, Dan; Bourgeois, Laure; Wang, Huanting; Webley, Paul A

2009-02-02

Nanochannel alumina templates are used as templates for fabrication of porous gold nanowire arrays by a direct electrodeposition method. After modification with glucose oxidase, a porous gold nanowire-array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose. The picture shows an SEM image of a nanowire array after removal of the alumina template by acid dissolution. We report the fabrication of porous gold nanowire arrays by means of a one-step electrodeposition method utilizing nanochannel alumina templates. The microstructure of gold nanowires depends strongly on the current density. The formation of porous gold nanowires is attributed to disperse crystallization under conditions of low nucleation rate. Interfacial electron transport through the porous gold nanowires is studied by electrochemical impedance spectroscopy. Cyclic voltammetric studies on the porous gold nanowire arrays reveal a low-potential electrocatalytic response towards hydrogen peroxide. The properties of the glucose oxidase modified porous gold nanowire array electrode are elucidated and compared with those of nonporous enzyme electrodes. The glucose oxidase modified porous gold nanowire-array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose.

EDTA assisted synthesis of hydroxyapatite nanoparticles for electrochemical sensing of uric acid.

PubMed

Kanchana, P; Sekar, C

2014-09-01

Hydroxyapatite nanoparticles have been synthesized using EDTA as organic modifier by a simple microwave irradiation method and its application for the selective determination of uric acid (UA) has been demonstrated. Electrochemical behavior of uric acid at HA nanoparticle modified glassy carbon electrode (E-HA/GCE) has been investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV) and amperometry. The E-HA modified electrode exhibits efficient electrochemical activity towards uric acid sensing without requiring enzyme or electron mediator. Amperometry studies revealed that the fabricated electrode has excellent sensitivity for uric acid with the lowest detection limit of 142 nM over a wide concentration range from 1 × 10(-7) to 3 × 10(-5)M. Moreover, the studied E-HA modified GC electrode exhibits a good reproducibility and long-term stability and an admirable selectivity towards the determination of UA even in the presence of potential interferents. The analytical performance of this sensor was evaluated for the detection of uric acid in human urine and blood serum samples. Copyright © 2014. Published by Elsevier B.V.

Experimental study of electrolysis-induced hepatic necrosis.

PubMed

Robertson, G S; Wemyss-Holden, S A; Dennison, A R; Hall, P M; Baxter, P; Maddern, G J

1998-09-01

One of the most promising but unexplored methods for treating patients with irresectable liver tumours is electrolysis. This study examined the effect of increasing 'current dose' on the volume of the lesion induced in normal rat liver. A direct current generator, connected to platinum electrodes implanted in the rat liver, was used to examine the effect of (1) varying current doses from 1 to 5 coulombs and (2) electrode separation (2 or 20 mm), on the volume of liver necrosis. There was a significant correlation (P < 0.001) between the current dose and the volume of necrosis produced for each electrode separation. Placing the electrodes 2 mm apart resulted in smaller total volumes of necrosis than placing them 20 mm apart when anode lesions were significantly larger than cathode lesions (P< 0.05). Liver enzymes (aspartate aminotransferase, alanine aminotransferase) were significantly raised 1 day after treatment (P < 0.001) and predicted the total volume of hepatic necrosis (P < 0.001). Predictable and reproducible areas of liver necrosis are produced with electrolysis. If these results extrapolate to larger animal models, this technique has potential for patients with irresectable primary and secondary liver tumours.

Schiff Base modified on CPE electrode and PCB gold electrode for selective determination of silver ion

NASA Astrophysics Data System (ADS)

Leepheng, Piyawan; Suramitr, Songwut; Phromyothin, Darinee

2017-09-01

The schiff base was synthesized by 2,5-thiophenedicarboxaldehyde and 1,2,4-thiadiazole-3,5-diamine with condensation method. There was modified on carbon paste electrode (CPE) and Printed circuit board (PCB) gold electrode for determination silver ion. The schiff base modified electrodes was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The electrochemical study was reported by cyclic voltammetry method and impedance spectroscopy using modified electrode as working electrode, platinum wire and Ag/AgCl as counter electrode and reference electrode, respectively. The modified electrodes have suitable detection for Ag+. The determination of silver ions using the modified electrodes depended linearly on Ag+ concentration in the range 1×10-10 M to 1×10-7 M, with cyclic voltammetry sensitivity were 2.51×108 μAM-1 and 1.88×108 μAM-1 for PCB gold electrode and CPE electrode, respectively, limits of detection were 5.33×10-9 M and 1.99×10-8 M for PCB gold electrode and CPE electrode, respectively. The modified electrodes have high accuracy, inexpensive and can applied to detection Ag+ in real samples.

Yeast surface displaying glucose oxidase as whole-cell biocatalyst: construction, characterization, and its electrochemical glucose sensing application.

PubMed

Wang, Hongwei; Lang, Qiaolin; Li, Liang; Liang, Bo; Tang, Xiangjiang; Kong, Lingrang; Mascini, Marco; Liu, Aihua

2013-06-18

The display of glucose oxidase (GOx) on yeast cell surface using a-agglutinin as an anchor motif was successfully developed. Both the immunochemical analysis and enzymatic assay showed that active GOx was efficiently expressed and translocated on the cell surface. Compared with conventional GOx, the yeast cell surface that displayed GOx (GOx-yeast) demonstrated excellent enzyme properties, such as good stability within a wide pH range (pH 3.5-11.5), good thermostability (retaining over 94.8% enzyme activity at 52 °C and 84.2% enzyme activity at 56 °C), and high d-glucose specificity. In addition, direct electrochemistry was achieved at a GOx-yeast/multiwalled-carbon-nanotube modified electrode, suggesting that the host cell of yeast did not have any adverse effect on the electrocatalytic property of the recombinant GOx. Thus, a novel electrochemical glucose biosensor based on this GOx-yeast was developed. The as-prepared biosensor was linear with the concentration of d-glucose within the range of 0.1-14 mM and a low detection limit of 0.05 mM (signal-to-noise ratio of S/N = 3). Moreover, the as-prepared biosensor is stable, specific, reproducible, simple, and cost-effective, which can be applicable for real sample detection. The proposed strategy to construct robust GOx-yeast may be applied to explore other oxidase-displaying-system-based whole-cell biocatalysts, which can find broad potential application in biosensors, bioenergy, and industrial catalysis.

Paper-based electrochemical sensor for on-site detection of the sulphur mustard.

PubMed

Colozza, Noemi; Kehe, Kai; Popp, Tanja; Steinritz, Dirk; Moscone, Danila; Arduini, Fabiana

2018-06-22

Herein, we report a novel paper-based electrochemical sensor for on-site detection of sulphur mustards. This sensor was conceived combining office paper-based electrochemical sensor with choline oxidase enzyme to deliver a sustainable sensing tool. The mustard agent detection relies on the evaluation of inhibition degree of choline oxidase, which is reversibly inhibited by sulphur mustards, by measuring the enzymatic by-product H 2 O 2 in chronoamperometric mode. A nanocomposite constituted of Prussian Blue nanoparticles and Carbon Black was used as working electrode modifier to improve the electroanalytical performances. This bioassay was successfully applied for the measurement of a sulphur mustard, Yprite, obtaining a detection limit in the millimolar range (LOD = 0.9 mM). The developed sensor, combined with a portable and easy-to-use instrumentation, can be applied for a fast and cost-effective detection of sulphur mustards.

Direct electrochemistry and intramolecular electron transfer of ascorbate oxidase confined on L-cysteine self-assembled gold electrode.

PubMed

Patil, Bhushan; Kobayashi, Yoshiki; Fujikawa, Shigenori; Okajima, Takeyoshi; Mao, Lanqun; Ohsaka, Takeo

2014-02-01

A direct electrochemistry and intramolecular electron transfer of multicopper oxidases are of a great importance for the fabrication of these enzyme-based bioelectrochemical-devices. Ascorbate oxidase from Acremonium sp. (ASOM) has been successfully immobilized via a chemisorptive interaction on the l-cysteine self-assembled monolayer modified gold electrode (cys-SAM/AuE). Thermodynamics and kinetics of adsorption of ASOM on the cys-SAM/AuE were studied using cyclic voltammetry. A well-defined redox wave centered at 166±3mV (vs. Ag│AgCl│KCl(sat.)) was observed in 5.0mM phosphate buffer solution (pH7.0) at the fabricated ASOM electrode, abbreviated as ASOM/cys-SAM/AuE, confirming a direct electrochemistry, i.e., a direct electron transfer (DET) between ASOM and cys-SAM/AuE. The direct electrochemistry of ASOM was further confirmed by taking into account the chemical oxidation of ascorbic acid (AA) by O2 via an intramolecular electron transfer in the ASOM as well as the electrocatalytic oxidation of AA at the ASOM/cys-SAM/AuE. Thermodynamics and kinetics of the adsorption of ASOM on the cys-SAM/AuE have been elaborated along with its direct electron transfer at the modified electrodes on the basis of its intramolecular electron transfer and electrocatalytic activity towards ascorbic acid oxidation and O2 reduction. ASOM saturated surface area was obtained as 2.41×10(-11)molcm(-2) with the apparent adsorption coefficient of 1.63×10(6)Lmol(-1). The ASOM confined on the cys-SAM/AuE possesses its essential enzymatic function. © 2013.

A Novel Photoelectrochemical Biosensor for Tyrosinase and Thrombin Detection

PubMed Central

Chen, Jiexia; Liu, Yifan; Zhao, Guang-Chao

2016-01-01

A novel photoelectrochemical biosensor for step-by-step assay of tyrosinase and thrombin was fabricated based on the specific interactions between the designed peptide and the target enzymes. A peptide chain with a special sequence which contains a positively charged lysine-labeled terminal, tyrosine at the other end and a cleavage site recognized by thrombin between them was designed. The designed peptide can be fixed on surface of the CdTe quantum dots (QDs)-modified indium-tin oxide (ITO) electrode through electrostatic attraction to construct the photoelectrochemical biosensor. The tyrosinase target can catalyze the oxidization of tyrosine by oxygen into ortho-benzoquinone residues, which results in a decrease in the sensor photocurrent. Subsequently, the cleavage site could be recognized and cut off by another thrombin target, restoring the sensor photocurrent. The decrease or increase of photocurrent in the sensor enables us to assay tyrosinase and thrombin. Thus, the detection of tyrosinase and thrombin can be achieved in the linear range from 2.6 to 32 μg/mL and from 4.5 to 100 μg/mL with detection limits of 1.5 μg/mL and 1.9 μg/mL, respectively. Most importantly, this strategy shall allow us to detect different classes of enzymes simultaneously by designing various enzyme-specific peptide substrates. PMID:26805846

Invisible Base Electrode Coordinates Approximation for Simultaneous SPECT and EEG Data Visualization

NASA Astrophysics Data System (ADS)

Kowalczyk, L.; Goszczynska, H.; Zalewska, E.; Bajera, A.; Krolicki, L.

2014-04-01

This work was performed as part of a larger research concerning the feasibility of improving the localization of epileptic foci, as compared to the standard SPECT examination, by applying the technique of EEG mapping. The presented study extends our previous work on the development of a method for superposition of SPECT images and EEG 3D maps when these two examinations are performed simultaneously. Due to the lack of anatomical data in SPECT images it is a much more difficult task than in the case of MRI/EEG study where electrodes are visible in morphological images. Using the appropriate dose of radioisotope we mark five base electrodes to make them visible in the SPECT image and then approximate the coordinates of the remaining electrodes using properties of the 10-20 electrode placement system and the proposed nine-ellipses model. This allows computing a sequence of 3D EEG maps spanning on all electrodes. It happens, however, that not all five base electrodes can be reliably identified in SPECT data. The aim of the current study was to develop a method for determining the coordinates of base electrode(s) missing in the SPECT image. The algorithm for coordinates approximation has been developed and was tested on data collected for three subjects with all visible electrodes. To increase the accuracy of the approximation we used head surface models. Freely available model from Oostenveld research based on data from SPM package and our own model based on data from our EEG/SPECT studies were used. For data collected in four cases with one electrode not visible we compared the invisible base electrode coordinates approximation for Oostenveld and our models. The results vary depending on the missing electrode placement, but application of the realistic head model significantly increases the accuracy of the approximation.

Double-Sided Transparent TiO2 Nanotube/ITO Electrodes for Efficient CdS/CuInS2 Quantum Dot-Sensitized Solar Cells

NASA Astrophysics Data System (ADS)

Chen, Chong; Ling, Lanyu; Li, Fumin

2017-01-01

In this paper, to improve the power conversion efficiencies (PCEs) of quantum dot-sensitized solar cells (QDSSCs) based on CdS-sensitized TiO2 nanotube (TNT) electrodes, two methods are employed on the basis of our previous work. First, by replacing the traditional single-sided working electrodes, double-sided transparent TNT/ITO (DTTO) electrodes are prepared to increase the loading amount of quantum dots (QDs) on the working electrodes. Second, to increase the light absorption of the CdS-sensitized DTTO electrodes and improve the efficiency of charge separation in CdS-sensitized QDSSCs, copper indium disulfide (CuInS2) is selected to cosensitize the DTTO electrodes with CdS, which has a complementary property of light absorption with CdS. The PCEs of QDSSCs based on these prepared QD-sensitized DTTO electrodes are measured. Our experimental results show that compared to those based on the CdS/DTTO electrodes without CuInS2, the PCEs of the QDSSCs based on CdS/CuInS2-sensitized DTTO electrode are significantly improved, which is mainly attributed to the increased light absorption and reduced charge recombination. Under simulated one-sun illumination, the best PCE of 1.42% is achieved for the QDSSCs based on CdS(10)/CuInS2/DTTO electrode, which is much higher than that (0.56%) of the QDSSCs based on CdS(10)/DTTO electrode.

Comparison of Foam-Based and Spring-Loaded Dry EEG Electrodes with Wet Electrodes in Resting and Moving Conditions*

PubMed Central

Yeung, Arnold; Garudadri, Harinath; Van Toen, Carolyn; Mercier, Patrick; Balkan, Ozgur; Makeig, Scott; Virji-Babul, Naznin

2018-01-01

The introduction of dry electrodes for EEG measurements has opened up possibilities of recording EEG outside of standard clinical environments by reducing required preparation and maintenance. However, the signal quality of dry electrodes in comparison with wet electrodes has not yet been evaluated under activities of daily life (ADL) or high motion tasks. In this study, we compared the performances of foam-based and spring-loaded dry electrodes with wet electrodes under three different task conditions: resting state, walking, and cycling. Our analysis showed signals obtained by the 2 types of dry electrodes and obtained by wet electrodes displayed high correlation for all conditions, while being prone to similar environmental and electrode-based artifacts. Overall, our results suggest that dry electrodes have a similar signal quality in comparison to wet electrodes and may be more practical for use in mobile and real-time motion applications due to their convenience. In addition, we conclude that as with wet electrodes, post-processing can mitigate motion artifacts in ambulatory EEG acquisition. PMID:26737936

Recent advances in graphite powder-based electrodes.

PubMed

Bellido-Milla, Dolores; Cubillana-Aguilera, Laura Ma; El Kaoutit, Mohammed; Hernández-Artiga, Ma Purificación; Hidalgo-Hidalgo de Cisneros, José Luis; Naranjo-Rodríguez, Ignacio; Palacios-Santander, José Ma

2013-04-01

Graphite powder-based electrodes have the electrochemical performance of quasi-noble metal electrodes with intrinsic advantages related to the possibility of modification to enhance selectivity and their easily renewable surface, with no need for hazardous acids or bases for their cleaning. In contrast with commercial electrodes, for example screen-printed or sputtered-chip electrodes, graphite powder-based electrodes can also be fabricated in any laboratory with the form and characteristics desired. They are also readily modified with advanced materials, with relatively high reproducibility. All these characteristics make them a very interesting option for obtaining a large variety of electrodes to resolve different kinds of analytical problems. This review summarizes the state-of-the-art, advantages, and disadvantages of graphite powder-based electrodes in electrochemical analysis in the 21st century. It includes recent trends in carbon paste electrodes, devoting special attention to the use of emergent materials as new binders and to the development of other composite electrodes. The most recent advances in the use of graphite powder-modified sol-gel electrodes are also described. The development of sonogel-carbon electrodes and their use in electrochemical sensors and biosensors is included. These materials extend the possibilities of applications, especially for industrial technology-transfer purposes, and their development could affect not only electroanalytical green chemistry but other interesting areas also, for example catalysis and energy conversion and storage.

Advanced membrane electrode assemblies for fuel cells

DOEpatents

Kim, Yu Seung; Pivovar, Bryan S.

2012-07-24

A method of preparing advanced membrane electrode assemblies (MEA) for use in fuel cells. A base polymer is selected for a base membrane. An electrode composition is selected to optimize properties exhibited by the membrane electrode assembly based on the selection of the base polymer. A property-tuning coating layer composition is selected based on compatibility with the base polymer and the electrode composition. A solvent is selected based on the interaction of the solvent with the base polymer and the property-tuning coating layer composition. The MEA is assembled by preparing the base membrane and then applying the property-tuning coating layer to form a composite membrane. Finally, a catalyst is applied to the composite membrane.

Advanced membrane electrode assemblies for fuel cells

DOEpatents

Kim, Yu Seung; Pivovar, Bryan S

2014-02-25

A method of preparing advanced membrane electrode assemblies (MEA) for use in fuel cells. A base polymer is selected for a base membrane. An electrode composition is selected to optimize properties exhibited by the membrane electrode assembly based on the selection of the base polymer. A property-tuning coating layer composition is selected based on compatibility with the base polymer and the electrode composition. A solvent is selected based on the interaction of the solvent with the base polymer and the property-tuning coating layer composition. The MEA is assembled by preparing the base membrane and then applying the property-tuning coating layer to form a composite membrane. Finally, a catalyst is applied to the composite membrane.

Sensitive amperometric biosensor for the determination of biogenic and synthetic amines using pea seedlings amine oxidase: a novel approach for enzyme immobilisation.

PubMed

Wimmerová, M; Macholán, L

1999-12-01

We prepared a new inorganic sorbent based on modified triazine (2-[4,6-bis (aminoethylamine)-1,3,5-triazine]-Silasorb; BAT-Silasorb) which binds pea seedlings amine oxidase (PSAO) very tightly without loss of its catalytic activity. This unique feature as well as the wide substrate specificity of PSAO was successfully utilised in the construction of an amperometric biosensor based on a carbon paste electrode for the fast and sensitive detection of various amines at a formal potential 0 mV versus Ag/AgCl reference electrode. The reaction layer of the biosensor is created by the direct immobilisation of PSAO at the electrode surface via affinity carrier BAT-Silasorb. Used arrangement facilitates a simple restoration of the inactive biosensor. An amperometric signal results from horseradish peroxidase catalysed reduction of H2O2, a secondary product of the oxidative deamination of amines, catalysed by PSAO. The sensor was used for the basic characterisation of 55 biogenic and synthetic amines, from numerous mono-, di- and polyamines to various hydroxy-, thio-, benzyl- and aromatic derivatives in order to establish its suitability as a postcolumn detector. Its high sensitivity to putrescine 20.0 +/- 0.64 mA l-1 per mol (636.9 +/- 2.03 mA l-1 per mol per cm2), a limit of detection of 10 nmol l-1 (determined with respect to a signal-to-noise ratio 3:1), a linear range of current response to 0.01-100 mumol l-1 concentration of substrate and good reproducibility all indicate that the sensor could be applied to future industrial and clinical analyses.

Design of a Sensitive and Selective Electrochemical Aptasensor for the Determination of the Complementary cDNA of miRNA-145 Based on the Intercalation and Electrochemical Reduction of Doxorubicin.

PubMed

Mohamadi, Maryam; Mostafavi, Ali; Torkzadeh-Mahani, Masoud

2017-11-01

The aim of this research was the determination of a microRNA (miRNA) using a DNA electrochemical aptasensor. In this biosensor, the complementary complementary DNA (cDNA) of miRNA-145 (a sense RNA transcript) was the target strand and the cDNA of miRNA-145 was the probe strand. Both cDNAs can be the product of the reverse transcriptase-polymerase chain reaction of miRNA. The proposed aptasensor's function was based on the hybridization of target strands with probes immobilized on the surface of a working electrode and the subsequent intercalation of doxorubicin (DOX) molecules functioning as the electroactive indicators of any double strands that formed. Electrochemical transduction was performed by measuring the cathodic current resulting from the electrochemical reduction of the intercalated molecules at the electrode surface. In the experiment, because many DOX molecules accumulated on each target strand on the electrode surface, amplification was inherently easy, without a need for enzymatic or complicated amplification strategies. The proposed aptasensor also had the excellent ability to regenerate as a result of the melting of the DNA duplex. Moreover, the use of DNA probe strands obviated the challenges of working with an RNA probe, such as sensitivity to RNase enzyme. In addition to the linear relationship between the electrochemical signal and the concentration of the target strands that ranged from 2.0 to 80.0 nM with an LOD of 0.27 nM, the proposed biosensor was clearly capable of distinguishing between complementary (target strand) and noncomplementary sequences. The presented biosensor was successfully applied for the quantification of DNA strands corresponding to miRNA-145 in human serum samples.

Effects of Multi-Electrode Renal Denervation on Insulin Sensitivity and Glucose Metabolism in a Canine Model of Type 2 Diabetes Mellitus.

PubMed

Pan, Tao; Guo, Jin-He; Ling, Long; Qian, Yue; Dong, Yong-Hua; Yin, Hua-Qing; Zhu, Hai-Dong; Teng, Gao-Jun

2018-05-01

To evaluate the effects of multi-electrode catheter-based renal denervation (RDN) on insulin sensitivity and glucose metabolism in a type 2 diabetes mellitus (T2DM) canine model. Thirty-three dogs were divided equally into 3 groups: bilateral renal denervation (BRDN) group, left renal denervation (LRDN) group, and sham operation (SHAM) group. Body weight and blood biochemistry were measured at baseline, 20 weeks, and 32 weeks, and renal angiography and computerized tomographic (CT) angiography were determined before the procedure and 1 month, 2 months, and 3 months after the procedure. Western blot was used to identify the activities of gluconeogenic enzymes and insulin-signaling proteins. Fasting plasma glucose (9.64 ± 1.57 mmol/L vs 5.12 ± 1.08 mmol/L; P < .0001), fasting insulin (16.19 ± 1.43 mIU/mL vs 5.07 ± 1.13 mIU/mL; P < .0001), and homeostasis-model assessment of insulin resistance (HOMA-IR; 6.95 ± 1.33 vs 1.15 ± 0.33; P < .0001) in the BRDN group had significantly decreased at the 3-month follow-up compared with the SHAM group. Western blot analyses showed that RDN suppressed the gluconeogenetic genes, modulated insulin action, and activated insulin receptors-AKT signaling cascade in the liver. CT angiography and histopathologic analyses did not show any dissection, aneurysm, thrombus, or rupture in any of the renal arteries. These findings identified that multi-electrode catheter-based RDN could effectively decrease gluconeogenesis and glycogenolysis, resulting in improvements in insulin sensitivity and glucose metabolism in a T2DM canine model. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

Development and Electrochemical Investigations of an EIS- (Electrolyte-Insulator-Semiconductor) based Biosensor for Cyanide Detection

PubMed Central

Turek, Monika; Ketterer, Lothar; Claβen, Melanie; Berndt, Heinz K.; Elbers, Gereon; Krüger, Peter; Keusgen, Michael; Schöning, Michael J.

2007-01-01

A cyanide biosensor based on a pH-sensitive p-doped electrolyte-insulator-semiconductor (EIS) structure with an immobilised enzyme (cyanidase) is realised at the laboratory scale. The immobilisation of the cyanidase is performed in two distinct steps: first, the covalent coupling of cyanidase to an N-hydroxysuccinimide- (NHS) activated Sepharose™ gel and then, the physical entrapment of NHS-activated Sepharose™ with the immobilised cyanidase in a dialysis membrane onto the EIS structure. The immobilisation of the cyanidase to the NHS-activated Sepharose™ is studied by means of gel electrophoresis measurements and investigations using an ammonia- (NH3) selective electrode. For the electrochemical characterisation of the cyanide biosensor, capacitance/voltage and constant capacitance measurements, respectively, have been carried out. A differential measurement procedure is presented to evaluate the cyanide concentration-dependent biosensor signals.

Production and purification of a soluble hydrogenase from Ralstonia eutropha H16 for potential hydrogen fuel cell applications.

PubMed

Jugder, Bat-Erdene; Lebhar, Helene; Aguey-Zinsou, Kondo-Francois; Marquis, Christopher P

2016-01-01

The soluble hydrogenase (SH) from Ralstonia eutropha H16 is a promising candidate enzyme for H2-based biofuel application as it favours H2 oxidation and is relatively oxygen-tolerant. In this report, bioprocess development studies undertaken to produce and purify an active SH are described, based on the methods previously reported [1], [2], [3], [4]. Our modifications are: •Upstream method optimizations were undertaken on heterotrophic growth media and cell lysis involving ultrasonication.•Two anion exchangers (Q Sepharose and RESOURCE Q) and size exclusion chromatographic (Superdex 200) matrices were successfully employed for purification of a hexameric SH from R. eutropha.•The H2 oxidizing activity of the SH was demonstrated spectrophotometrically in solution and also immobilized on an EPG electrode using cyclic voltammetry.

[Fabrication and evaluation of the enzyme immunosensor for rapid detection of Vibrio parahaemolyticus based on chitosan-SiO2 hybrid membrane].

PubMed

Zhao, Guang-Ying; Ma, Chao; Li, Jian-Rong

2010-01-01

To improve the key technology of immunesensors in immobilizing bio-sensitive element and keeping its bioactivity, an enzyme immunosensor based on chitosan-SiO(2) (CS-Sio(2)) hybrid membrane was fabricated. To estimate the new immunosensor Vibrio parahaemolyticus which was the main pathogens of aquatic products. A CS-SiO(2) hybrid membrane was prepared using sol-gel method. The enzyme immunosensor was fabricated by coating the membrane and horseradish peroxidase labeled Vibrio parahaemolyticus antibody (HRP-anti-VP) on the surface of four-channel screen-printed carbon electrode. The immunosensor was characterized by cyclic voltammetry. Vibrio parahaemolyticus could be detected according to the decrease percentage (DP) of peak current before and after immune response, while cyclic voltammetry was used as an electrochemical mean to detect the products of the enzymatic reaction. Seven kinds of bacteria, like Vibrio alginolyticus, were selected for specific experiments. By studying the infrared spectrum of three kinds of films, the CS-SiO(2) hybrid membrane was prepared and HRP-anti-VP was fixed in the hybrid membrane. Under the optimum conditions of immunoreaction and electrochemical detection, the DP of peak current before and after immune response showed a linear relation with lgC in the range of 10(4) - 10(9) cfu/ml, while the linear regression equation was: DP = 6.5 lgC-3.319, the correlation coefficient was 0.9958 and the detection limit was 6.9 x 10(3) cfu/ml (S/N = 3). The immunosensor possessed acceptable specificity, reproducibility (RSD < 6%), stability (the amperometric response was 95% of the initial response after a week) and accuracy (96.7% of the results obtained by the immunosensor were in agreement with those obtained by GB/T 4789.7-2003). The enzyme immunosensor based on CS-SiO(2) hybrid membrane gave a good performance in rapid detection of Vibrio parahaemolyticus.

Improving the direct electron transfer in monolithic bioelectrodes prepared by immobilization of FDH enzyme on carbon-coated anodic aluminum oxide films

NASA Astrophysics Data System (ADS)

Castro-Muñiz, Alberto; Hoshikawa, Yasuto; Komiyama, Hiroshi; Nakayama, Wataru; Itoh, Tetsuji; Kyotani, Takashi

2016-02-01

The present work reports the preparation of binderless carbon-coated porous films and the study of their performance as monolithic bioanodes. The films were prepared by coating anodic aluminum oxide (AAO) films with a thin layer of nitrogen-doped carbon by chemical vapor deposition. The films have cylindrical straight pores with controllable diameter and length. These monolithic films were used directly as bioelectrodes by loading the films with D-fructose dehydrogenase (FDH), an oxidoreductase enzyme that catalyzes the oxidation of D-fructose to 5-keto-D-fructose. The immobilization of the enzymes was carried out by physical adsorption in liquid phase and with an electrostatic attraction method. The latter method takes advantage of the fact that FDH is negatively charged during the catalytic oxidation of fructose. Thus the immobilization was performed under the application of a positive voltage to the CAAO film in a FDH-fructose solution in McIlvaine buffer (pH 5) at 25 ºC. As a result, the FDH modified electrodes with the latter method show much better electrochemical response than that with the conventional physical adsorption method. Due to the singular porous structure of the monolithic films, which consists of an array of straight and parallel nanochannels, it is possible to rule out the effect of the diffusion of the D-fructose into the pores. Thus the improvement in the performance upon using the electrostatic attraction method can be ascribed not only to a higher uptake, but also to a more appropriate molecule orientation of the enzyme units on the surface of the electrodes.

Carbon Nanotube Based Light Sensor

NASA Technical Reports Server (NTRS)

Wincheski, russell A. (Inventor); Smits, Jan M. (Inventor); Jordan, Jeffrey D. (Inventor); Watkins, Anthony Neal (Inventor); Ingram, JoAnne L. (Inventor)

2006-01-01

A light sensor substrate comprises a base made from a semi-conductive material and topped with a layer of an electrically non-conductive material. A first electrode and a plurality of carbon nanotube (CNT)-based conductors are positioned on the layer of electrically non-conductive material with the CNT-based conductors being distributed in a spaced apart fashion about a periphery of the first electrode. Each CNT-based conductor is coupled on one end thereof to the first electrode and extends away from the first electrode to terminate at a second free end. A second or gate electrode is positioned on the non-conductive material layer and is spaced apart from the second free end of each CNT-based conductor. Coupled to the first and second electrode is a device for detecting electron transfer along the CNT-based conductors resulting from light impinging on the CNT-based conductors.

Wearable carbon nanotube based dry-electrodes for electrophysiological sensors

NASA Astrophysics Data System (ADS)

Kang, Byeong-Cheol; Ha, Tae-Jun

2018-05-01

In this paper, we demonstrate all-solution-processed carbon nanotube (CNT) dry-electrodes for the detection of electrophysiological signals such as electrocardiograms (ECG) and electromyograms (EMG). The key parameters of P, Q, R, S, and T peaks are successfully extracted by such CNT based dry-electrodes, which is comparable with conventional silver/chloride (Ag/AgCl) wet-electrodes with a conducting gel film for the ECG recording. Furthermore, the sensing performance of CNT based dry-electrodes is secured during the bending test of 200 cycles, which is essential for wearable electrophysiological sensors in a non-invasive method on human skin. We also investigate the application of wearable CNT based dry-electrodes directly attached to the human skins such as forearm for sensing the electrophysiological signals. The accurate and rapid sensing response can be achieved by CNT based dry-electrodes to supervise the health condition affected by excessive physical movements during the real-time measurements.

High efficiency iron electrode and additives for use in rechargeable iron-based batteries

DOEpatents

Narayan, Sri R.; Prakash, G. K. Surya; Aniszfeld, Robert; Manohar, Aswin; Malkhandi, Souradip; Yang, Bo

2017-02-21

An iron electrode and a method of manufacturing an iron electrode for use in an iron-based rechargeable battery are disclosed. In one embodiment, the iron electrode includes carbonyl iron powder and one of a metal sulfide additive or metal oxide additive selected from the group of metals consisting of bismuth, lead, mercury, indium, gallium, and tin for suppressing hydrogen evolution at the iron electrode during charging of the iron-based rechargeable battery. An iron-air rechargeable battery including an iron electrode comprising carbonyl iron is also disclosed, as is an iron-air battery wherein at least one of the iron electrode and the electrolyte includes an organosulfur additive.

Vertically grown zinc oxide nanorods functionalized with ferric oxide for in vivo and non-enzymatic glucose detection

NASA Astrophysics Data System (ADS)

Marie, Mohammed; Manoharan, Anishkumar; Kuchuk, Andrian; Ang, Simon; Manasreh, M. O.

2018-03-01

An enzyme-free glucose sensor based on vertically grown zinc oxide nanorods (NRs) functionalized with ferric oxide (Fe2O3) is investigated. The well-aligned and high density ZnO NRs were synthesized on an FTO/glass substrate by a sol-gel and hydrothermal growth method. A dip-coating technique was utilized to modify the surface of the as-grown ZnO NRs with Fe2O3. The immobilized surface was coated with a layer of nafion membrane. The fabricated glucose sensor was characterized amperometrically at room temperature using three electrodes stationed in the phosphate buffer solution, where ZnO NRs/Fe2O3/nafion membrane was the sensing or working electrode, and platinum plate and silver/silver chloride were used as the counter and reference electrodes, respectively. The proposed non-enzymatic and modified glucose sensor exhibited a high sensitivity in the order of 0.052 μA cm-2 (mg/dL)-1, a lower detection limit of around 0.95 mmol L-1, a sharp and fast response time of ˜1 s, and a linear response to changes in glucose concentrations from 100-400 mg dL-1. The linear amperometric response of the sensor covers the physiological and clinical interest of glucose levels for diabetic patients. The device continues to function accurately after multiple measurements with a good reproducibility. The proposed glucose sensor is expected to be used clinically for in vivo monitoring of glucose.

Aptamer-based assay for monitoring genetic disorder phenylketonuria (PKU).

PubMed

Hasanzadeh, Mohammad; Zargami, Amir; Baghban, Hossein Navay; Mokhtarzadeh, Ahad; Shadjou, Nasrin; Mahboob, Soltanali

2018-05-16

The genetic disorder phenylketonuria (PKU) is the inability to metabolize phenylalanine because of a lack of the enzyme phenylalanine hydroxylase. Phenylalanine is used to biochemically form proteins, coded for by DNA. The development of an apta-assay for detection of l-Phenylalanine is presented in this work. A highly specific DNA-aptamer, selected to l-Phenylalanine was immobilized onto a gold nanostructure and electrochemical measurements were performed in a solution containing the phosphate buffer solution with physiological pH. We have constructed an aptamer immobilized gold nanostructure mediated, ultrasensitive electrochemical biosensor (Apt/AuNSs/Au electrode) for l-Phenylalanine detection without any additional signal amplification strategy. The aptamer assemble onto the AuNSs makes Apt/AuNSs/Au electrode an excellent platform for the l-Phenylalanine detection in physiological like condition. Differential pulse voltammetry were used for the quantitative l-Phenylalanine detection. The Apt/AuNSs/Au electrode offers an ultrasensitive and selective detection of l-Phenylalanine down to 0.23 μM level with a wide dynamic range from 0.72 μM-6 mM. The aptasensor exhibited excellent selectivity and stability. The real sample analysis was performed by spiking the unprocessed human serum samples with various concentration of l-Phenylalanine and obtained recovery within 2% error value. The sensor is found to be more sensitive than most of the literature reports. The simple and easy way of construction of this apta-assay provides an efficient and promising diagnosis of phenylketonuria. Copyright © 2018. Published by Elsevier B.V.

Biotin determination in food supplements by an electrochemical magneto biosensor.

PubMed

Kergaravat, Silvina V; Gómez, Gabriel A; Fabiano, Silvia N; Laube Chávez, Tamara I; Pividori, María I; Hernández, Silvia R

2012-08-15

An electrochemical magneto biosensor for the rapid determination of biotin in food samples is reported. The affinity reaction was performed on streptavidin-modified magnetic microbeads as a solid support in a direct competitive format. The biotinylated horseradish peroxidase enzyme (biotin-HRP) competes with free biotin in the sample for the binding sites of streptavidin on the magnetic microbeads. The modified magnetic beads were then easily captured by a magneto graphite-epoxy composite electrode and the electrochemical signal was based on the enzymatic activity of the HRP enzyme under the addition of H(2)O(2) as the substrate and o-phenilendiamine as cosubstrate. The response was electrochemically detected by square wave voltammetry. The limit of detection was 8.4×10(-8) mol L(--1) of biotin (20 μg L(--1)) with a dynamic range from 0.94 to 2.4×10(-7) mol L(--1). Biotin-fortified commercial dietary supplement and infant formula samples were evaluated obtaining good performances in the results. Total time of analysis was 40 min per 20 assays. Copyright © 2012 Elsevier B.V. All rights reserved.

Nanostructured biosensors built by layer-by-layer electrostatic assembly of enzyme-coated single-walled carbon nanotubes and redox polymers.

PubMed

Wang, Youdan; Joshi, Pratixa P; Hobbs, Kevin L; Johnson, Matthew B; Schmidtke, David W

2006-11-07

In this study, we describe the construction of glucose biosensors based on an electrostatic layer-by-layer (LBL) technique. Gold electrodes were initially functionalized with negatively charged 11-mercaptoundecanoic acid followed by alternate immersion in solutions of a positively charged redox polymer, poly[(vinylpyridine)Os(bipyridyl)2Cl(2+/3+)], and a negatively charged enzyme, glucose oxidase (GOX), or a GOX solution containing single-walled carbon nanotubes (SWNTs). The LBL assembly of the multilayer films were characterized by UV-vis spectroscopy, ellipsometry, and cyclic voltammetry, while characterization of the single-walled nanotubes was performed with transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. When the GOX solution contained single-walled carbon nanotubes (GOX-SWNTs), the oxidation peak currents during cyclic voltammetry increased 1.4-4.0 times, as compared to films without SWNTs. Similarly the glucose electro-oxidation current also increased (6-17 times) when SWNTs were present. By varying the number of multilayers, the sensitivity of the sensors could be controlled.

Recent Progress in Iron-Based Electrode Materials for Grid-Scale Sodium-Ion Batteries.

PubMed

Fang, Yongjin; Chen, Zhongxue; Xiao, Lifen; Ai, Xinping; Cao, Yuliang; Yang, Hanxi

2018-03-01

Grid-scale energy storage batteries with electrode materials made from low-cost, earth-abundant elements are needed to meet the requirements of sustainable energy systems. Sodium-ion batteries (SIBs) with iron-based electrodes offer an attractive combination of low cost, plentiful structural diversity and high stability, making them ideal candidates for grid-scale energy storage systems. Although various iron-based cathode and anode materials have been synthesized and evaluated for sodium storage, further improvements are still required in terms of energy/power density and long cyclic stability for commercialization. In this Review, progress in iron-based electrode materials for SIBs, including oxides, polyanions, ferrocyanides, and sulfides, is briefly summarized. In addition, the reaction mechanisms, electrochemical performance enhancements, structure-composition-performance relationships, merits and drawbacks of iron-based electrode materials for SIBs are discussed. Such iron-based electrode materials will be competitive and attractive electrodes for next-generation energy storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fuel cell electrodes

DOEpatents

Strmcnik, Dusan; Cuesta, Angel; Stamenkovic, Vojislav; Markovic, Nenad

2015-06-23

A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

Augmented reality-based electrode guidance system for reliable electroencephalography.

PubMed

Song, Chanho; Jeon, Sangseo; Lee, Seongpung; Ha, Ho-Gun; Kim, Jonghyun; Hong, Jaesung

2018-05-24

In longitudinal electroencephalography (EEG) studies, repeatable electrode positioning is essential for reliable EEG assessment. Conventional methods use anatomical landmarks as fiducial locations for the electrode placement. Since the landmarks are manually identified, the EEG assessment is inevitably unreliable because of individual variations among the subjects and the examiners. To overcome this unreliability, an augmented reality (AR) visualization-based electrode guidance system was proposed. The proposed electrode guidance system is based on AR visualization to replace the manual electrode positioning. After scanning and registration of the facial surface of a subject by an RGB-D camera, the AR of the initial electrode positions as reference positions is overlapped with the current electrode positions in real time. Thus, it can guide the position of the subsequently placed electrodes with high repeatability. The experimental results with the phantom show that the repeatability of the electrode positioning was improved compared to that of the conventional 10-20 positioning system. The proposed AR guidance system improves the electrode positioning performance with a cost-effective system, which uses only RGB-D camera. This system can be used as an alternative to the international 10-20 system.

Effect of the electrical currents generated by the intestinal smooth muscle layers on pancreatic enzyme activity: an in vitro study.

PubMed

Dabek, Marta; Podgurniak, Paweł; Piedra, Jose L Valverde; Szymańczyk, Sylwia; Filip, Rafał; Wojtasz-Pajak, Anna; Werpachowska, Eliza; Podgurniak, Malgorzata; Pierzynowski, Stefan G

2007-05-01

Gut enzymes in the small intestine are exposed to extremely low electrical currents (ELEC) generated by the smooth muscle. In the present study, the in vitro tests were undertaken to evaluate the effect of these electric currents on the activity of the proteolytic pancreatic digestive enzymes. A simulator generating the typical electrical activity of pig gut was used for these studies. The electric current emitted by the simulator was transmitted to the samples, containing enzyme and its substrate, using platinum plate electrodes. All samples were incubated at 37 degrees C for 1 h. The changes in optical density, corresponding to enzyme activity, in samples stimulated for 1 h with ELEC was compared with that not exposed to ELEC. The obtained results show that the electrical current with the characteristics of the myoelectrical migrating complex (MMC) has an influence on pancreatic enzyme activity. Increased endopeptidase and reduced exopeptidase activity was noticed in samples treated with ELEC. This observation can be of important as analyzed factors which can alter enzymatic activity of the gut, can thus also affect feed/food digestibility. (c) 2007 Wiley-Liss, Inc.

A Multi-Parametric Device with Innovative Solid Electrodes for Long-Term Monitoring of pH, Redox-Potential and Conductivity in a Nuclear Waste Repository

PubMed Central

Daoudi, Jordan; Betelu, Stephanie; Tzedakis, Theodore; Bertrand, Johan; Ignatiadis, Ioannis

2017-01-01

We present an innovative electrochemical probe for the monitoring of pH, redox potential and conductivity in near-field rocks of deep geological radioactive waste repositories. The probe is composed of a monocrystalline antimony electrode for pH sensing, four AgCl/Ag-based reference or Cl− selective electrodes, one Ag2S/Ag-based reference or S2− selective electrode, as well as four platinum electrodes, a gold electrode and a glassy-carbon electrode for redox potential measurements. Galvanostatic electrochemistry impedance spectroscopy using AgCl/Ag-based and platinum electrodes measure conductivity. The use of such a multi-parameter probe provides redundant information, based as it is on the simultaneous behaviour under identical conditions of different electrodes of the same material, as well as on that of electrodes made of different materials. This identifies the changes in physical and chemical parameters in a solution, as well as the redox reactions controlling the measured potential, both in the solution and/or at the electrode/solution interface. Understanding the electrochemical behaviour of selected materials thus is a key point of our research, as provides the basis for constructing the abacuses needed for developing robust and reliable field sensors. PMID:28608820

A Multi-Parametric Device with Innovative Solid Electrodes for Long-Term Monitoring of pH, Redox-Potential and Conductivity in a Nuclear Waste Repository.

PubMed

Daoudi, Jordan; Betelu, Stephanie; Tzedakis, Theodore; Bertrand, Johan; Ignatiadis, Ioannis

2017-06-13

We present an innovative electrochemical probe for the monitoring of pH, redox potential and conductivity in near-field rocks of deep geological radioactive waste repositories. The probe is composed of a monocrystalline antimony electrode for pH sensing, four AgCl/Ag-based reference or Cl - selective electrodes, one Ag₂S/Ag-based reference or S 2- selective electrode, as well as four platinum electrodes, a gold electrode and a glassy-carbon electrode for redox potential measurements. Galvanostatic electrochemistry impedance spectroscopy using AgCl/Ag-based and platinum electrodes measure conductivity. The use of such a multi-parameter probe provides redundant information, based as it is on the simultaneous behaviour under identical conditions of different electrodes of the same material, as well as on that of electrodes made of different materials. This identifies the changes in physical and chemical parameters in a solution, as well as the redox reactions controlling the measured potential, both in the solution and/or at the electrode/solution interface. Understanding the electrochemical behaviour of selected materials thus is a key point of our research, as provides the basis for constructing the abacuses needed for developing robust and reliable field sensors.

Fully Textile, PEDOT:PSS Based Electrodes for Wearable ECG Monitoring Systems.

PubMed

Pani, Danilo; Dessi, Alessia; Saenz-Cogollo, Jose F; Barabino, Gianluca; Fraboni, Beatrice; Bonfiglio, Annalisa

2016-03-01

To evaluate a novel kind of textile electrodes based on woven fabrics treated with PSS, through an easy fabrication process, testing these electrodes for biopotential recordings. Fabrication is based on raw fabric soaking in PSS using a second dopant, squeezing and annealing. The electrodes have been tested on human volunteers, in terms of both skin contact impedance and quality of the ECG signals recorded at rest and during physical activity (power spectral density, baseline wandering, QRS detectability, and broadband noise). The electrodes are able to operate in both wet and dry conditions. Dry electrodes are more prone to noise artifacts, especially during physical exercise and mainly due to the unstable contact between the electrode and the skin. Wet (saline) electrodes present a stable and reproducible behavior, which is comparable or better than that of traditional disposable gelled Ag/AgCl electrodes. The achieved results reveal the capability of this kind of electrodes to work without the electrolyte, providing a valuable interface with the skin, due to mixed electronic and ionic conductivity of PSS. These electrodes can be effectively used for acquiring ECG signals. Textile electrodes based on PSS represent an important milestone in wearable monitoring, as they present an easy and reproducible fabrication process, very good performance in wet and dry (at rest) conditions and a superior level of comfort with respect to textile electrodes proposed so far. This paves the way to their integration into smart garments.

Evaluation of electrokinetic parameters for all DNA bases with sputter deposited nanocarbon film electrode.

PubMed

Kato, Dai; Sumimoto, Michinori; Ueda, Akio; Hirono, Shigeru; Niwa, Osamu

2012-12-18

The electrokinetic parameters of all the DNA bases were evaluated using a sputter-deposited nanocarbon film electrode. It is very difficult to evaluate the electrokinetic parameters of DNA bases with conventional electrodes, and particularly those of pyrimidine bases, owing to their high oxidation potentials. Nanocarbon film formed by employing an electron cyclotron resonance sputtering method consists of a nanocrystalline sp(2) and sp(3) mixed bond structure that exhibits a sufficient potential window, very low adsorption of DNA molecules, and sufficient electrochemical activity to oxidize all DNA bases. A precise evaluation of rate constants (k) between all the bases and the electrodes is achieved for the first time by obtaining rotating disc electrode measurements with our nanocarbon film electrode. We found that the k value of each DNA base was dominantly dependent on the surface oxygen-containing group of the nanocarbon film electrode, which was controlled by electrochemical pretreatment. In fact, the treated electrode exhibited optimum k values for all the mononucleotides, namely, 2.0 × 10(-2), 2.5 × 10(-1), 2.6 × 10(-3), and 5.6 × 10(-3) cm s(-1) for GMP, AMP, TMP, and CMP, respectively. The k value of AMP was sufficiently enhanced by up to 33 times with electrochemical pretreatment. We also found the k values for pyrimidine bases to be much lower than those of purine bases although there was no large difference between their diffusion coefficient constants. Moreover, the theoretical oxidation potential values for all the bases coincided with those obtained in electrochemical experiments using our nanocarbon film electrode.

Design, fabrication and skin-electrode contact analysis of polymer microneedle-based ECG electrodes

NASA Astrophysics Data System (ADS)

O'Mahony, Conor; Grygoryev, Konstantin; Ciarlone, Antonio; Giannoni, Giuseppe; Kenthao, Anan; Galvin, Paul

2016-08-01

Microneedle-based ‘dry’ electrodes have immense potential for use in diagnostic procedures such as electrocardiography (ECG) analysis, as they eliminate several of the drawbacks associated with the conventional ‘wet’ electrodes currently used for physiological signal recording. To be commercially successful in such a competitive market, it is essential that dry electrodes are manufacturable in high volumes and at low cost. In addition, the topographical nature of these emerging devices means that electrode performance is likely to be highly dependent on the quality of the skin-electrode contact. This paper presents a low-cost, wafer-level micromoulding technology for the fabrication of polymeric ECG electrodes that use microneedle structures to make a direct electrical contact to the body. The double-sided moulding process can be used to eliminate post-process via creation and wafer dicing steps. In addition, measurement techniques have been developed to characterize the skin-electrode contact force. We perform the first analysis of signal-to-noise ratio dependency on contact force, and show that although microneedle-based electrodes can outperform conventional gel electrodes, the quality of ECG recordings is significantly dependent on temporal and mechanical aspects of the skin-electrode interface.

An electrochemical acetylcholine sensor based on lichen-like nickel oxide nanostructure.

PubMed

Sattarahmady, N; Heli, H; Vais, R Dehdari

2013-10-15

Lichen-like nickel oxide nanostructure was synthesized by a simple method and characterized. The nanostructure was then applied to modify a carbon paste electrode and for the fabrication of a sensor, and the electrocatalytic oxidation of acetylcholine (ACh) on the modified electrode was investigated. The electrocatalytic efficiency of the nickel oxide nanostructure was compared with nickel micro- and nanoparticles, and the lichen-like nickel oxide nanostructure showed the highest efficiency. The mechanism and kinetics of the electrooxidation process were investigated by cyclic voltammetry, steady-state polarization curve and chronoamperometry. The catalytic rate constant and the charge transfer coefficient of ACh electrooxidation by the active nickel species, and the diffusion coefficient of ACh were reported. A sensitive and time-saving hydrodynamic amperometry method was developed for the determination of ACh. ACh was determined with a sensitivity of 392.4 mA M⁻¹ cm⁻² and a limit of detection of 26.7 μM. The sensor had the advantages of simple fabrication method without using any enzyme or reagent and immobilization step, high electrocatalytic activity, very high sensitivity, long-term stability, and antifouling surface property toward ACh and its oxidation product. Copyright © 2013 Elsevier B.V. All rights reserved.

Layer-by-Layer Self-Assembling Gold Nanorods and Glucose Oxidase onto Carbon Nanotubes Functionalized Sol-Gel Matrix for an Amperometric Glucose Biosensor.

PubMed

Wu, Baoyan; Hou, Shihua; Miao, Zhiying; Zhang, Cong; Ji, Yanhong

2015-09-18

A novel amperometric glucose biosensor was fabricated by layer-by-layer self-assembly of gold nanorods (AuNRs) and glucose oxidase (GOD) onto single-walled carbon nanotubes (SWCNTs)-functionalized three-dimensional sol-gel matrix. A thiolated aqueous silica sol containing SWCNTs was first assembled on the surface of a cleaned Au electrode, and then the alternate self-assembly of AuNRs and GOD were repeated to assemble multilayer films of AuNRs-GOD onto SWCNTs-functionalized silica gel for optimizing the biosensor. Among the resulting glucose biosensors, the four layers of AuNRs-GOD-modified electrode showed the best performance. The sol-SWCNTs-(AuNRs- GOD)₄/Au biosensor exhibited a good linear range of 0.01-8 mM glucose, high sensitivity of 1.08 μA/mM, and fast amperometric response within 4 s. The good performance of the proposed glucose biosensor could be mainly attributed to the advantages of the three-dimensional sol-gel matrix and stereo self-assembly films, and the natural features of one-dimensional nanostructure SWCNTs and AuNRs. This study may provide a new facile way to fabricate the enzyme-based biosensor with high performance.

An electrochemical microRNAs biosensor with the signal amplification of alkaline phosphatase and electrochemical-chemical-chemical redox cycling.

PubMed

Xia, Ning; Zhang, Youjuan; Wei, Xin; Huang, Yaping; Liu, Lin

2015-06-09

MicroRNAs (MiRNAs) have been regarded as clinically important biomarkers and drug discovery targets. In this work, we reported a simple and ultrasensitive electrochemical method for miRNAs detection based on single enzyme amplification and electrochemical-chemical-chemical (ECC) redox cycling. Specifically, upon contact with the target miRNAs, the hairpin structure of biotinylated DNA immobilized on gold electrode was destroyed and the biotin group in DNA was forced away from the electrode surface, allowing for the coupling of streptavidin-conjugated alkaline phosphatase (SA-ALP). Then, ascorbic acid (AA, the enzymatic product of ALP) triggered the ECC redox cycling with ferrocene methanol (FcM) and tris(2-carboxyethyl)phosphine (TCEP) as the redox mediator and the chemical reducing reagent, respectively. The method was more sensitive than that with horseradish peroxidase (HRP) or glucose oxidase (GOx) triggered recycling since one ALP molecule captured by one target miRNA molecule promoted the production of thousands of AA. Analytical merits (e.g., detection limit, dynamic range, specificity, regeneration and reproducibility) were evaluated. The feasibility of the method for analysis of miRNA-21 in human serum has also been demonstrated. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrochemically mediated electrodeposition/electropolymerization to yield a glucose microbiosensor with improved characteristics.

PubMed

Chen, Xiaohong; Matsumoto, Norio; Hu, Yibai; Wilson, George S

2002-01-15

A procedure is described that provides for electrochemically mediated deposition of enzyme and a polymer layer permselective for endogenous electroactive species. Electrodeposition was first employed for the direct immobilization of glucose oxidase to produce a uniform, thin, and compact film on a Pt electrode. Electropolymerization of phenol was then employed to form an anti-interference and protective polyphenol film within the enzyme layer. In addition, a stability-reinforcing membrane derived from (3-aminopropyl)trimethoxysilane was constructed by electrochemically assisted cross-linking. This hybrid film outside the enzyme layer contributed to the improved stability and permselectivity. The resulting glucose sensor was characterized by a short response time (<4 s), high sensitivity (1200 nA/mM x cm2), low interference from endogenous electroactive species, and working lifetime of more than 50 days.

Bioelectrochemical interface engineering: toward the fabrication of electrochemical biosensors, biofuel cells, and self-powered logic biosensors.

PubMed

Zhou, Ming; Dong, Shaojun

2011-11-15

Over the past decade, researchers have devoted considerable attention to the integration of living organisms with electronic elements to yield bioelectronic devices. Not only is the integration of DNA, enzymes, or whole cells with electronics of scientific interest, but it has many versatile potential applications. Researchers are using these ideas to fabricate biosensors for analytical applications and to assemble biofuel cells (BFCs) and biomolecule-based devices. Other research efforts include the development of biocomputing systems for information processing. In this Account, we focus on our recent progress in engineering at the bioelectrochemical interface (BECI) for the rational design and construction of important bioelectronic devices, ranging from electrochemical (EC-) biosensors to BFCs, and self-powered logic biosensors. Hydrogels and sol-gels provide attractive materials for the immobilization of enzymes because they make EC-enzyme biosensors stable and even functional in extreme environments. We use a layer-by-layer (LBL) self-assembly technique to fabricate multicomponent thin films on the BECI at the nanometer scale. Additionally, we demonstrate how carbon nanomaterials have paved the way for new and improved EC-enzyme biosensors. In addition to the widely reported BECI-based electrochemical impedance spectroscopy (EIS)-type aptasensors, we integrate the LBL technique with our previously developed "solid-state probe" technique for redox probes immobilization on electrode surfaces to design and fabricate BECI-based differential pulse voltammetry (DPV)-type aptasensors. BFCs can directly harvest energy from ambient biofuels as green energy sources, which could lead to their application as simple, flexible, and portable power sources. Porous materials provide favorable microenvironments for enzyme immobilization, which can enhance BFC power output. Furthermore, by introducing aptamer-based logic systems to BFCs, such systems could be applied as self-powered and intelligent aptasensors for the logic detection. We have developed biocomputing keypad lock security systems which can be also used for intelligent medical diagnostics. BECI engineering provides a simple but effective approach toward the design and fabrication of EC-biosensors, BFCs, and self-powered logic biosensors, which will make essential contributions in the development of creative and practical bioelectronic devices. The exploration of novel interface engineering applications and the creation of new fabrication concepts or methods merit further attention.

Self-Assembled Films of Dendrimers and Metallophthalocyanines as FET-Based Glucose Biosensors

PubMed Central

Vieira, Nirton C.S.; Figueiredo, Alessandra; de Queiroz, Alvaro A.A.; Zucolotto, Valtencir; Guimarães, Francisco E.G.

2011-01-01

Separative extended gate field effect transistor (SEGFET) type devices have been used as an ion sensor or biosensor as an alternative to traditional ion sensitive field effect transistors (ISFETs) due to their robustness, ease of fabrication, low cost and possibility of FET isolation from the chemical environment. The layer-by-layer technique allows the combination of different materials with suitable properties for enzyme immobilization on simple platforms such as the extended gate of SEGFET devices enabling the fabrication of biosensors. Here, glucose biosensors based on dendrimers and metallophthalocyanines (MPcs) in the form of layer-by-layer (LbL) films, assembled on indium tin oxide (ITO) as separative extended gate material, has been produced. NH3+ groups in the dendrimer allow electrostatic interactions or covalent bonds with the enzyme (glucose oxidase). Relevant parameters such as optimum pH, buffer concentration and presence of serum bovine albumin (BSA) in the immobilization process were analyzed. The relationship between the output voltage and glucose concentration shows that upon detection of a specific analyte, the sub-products of the enzymatic reaction change the pH locally, affecting the output signal of the FET transducer. In addition, dendritic layers offer a nanoporous environment, which may be permeable to H+ ions, improving the sensibility as modified electrodes for glucose biosensing. PMID:22163704

Facile and controllable preparation of glucose biosensor based on Prussian blue nanoparticles hybrid composites.

PubMed

Li, Lei; Sheng, Qinglin; Zheng, Jianbin; Zhang, Hongfang

2008-11-01

A glucose biosensor based on polyvinylpyrrolidone (PVP) protected Prussian blue nanoparticles (PBNPs)-polyaniline/multi-walled carbon nanotubes hybrid composites was fabricated by electrochemical method. A novel route for PBNPs preparation was applied in the fabrication with the help of PVP, and from scanning electron microscope images, Prussian blue particles on the electrode were found nanoscaled. The biosensor exhibits fast current response (<6 s) and a linearity in the range from 6.7x10(-6) to 1.9x10(-3) M with a high sensitivity of 6.28 microA mM(-1) and a detection limit of 6x10(-7) M (S/N=3) for the detection of glucose. The apparent activation energy of enzyme-catalyzed reaction and the apparent Michaelis-Menten constant are 23.9 kJ mol(-1) and 1.9 mM respectively, which suggests a high affinity of the enzyme-substrate. This easy and controllable construction method of glucose biosensor combines the characteristics of the components of the hybrid composites, which favors the fast and sensitive detection of glucose with improved analytical capabilities. In addition, the biosensor was examined in human serum samples for glucose determination with a recovery between 95.0 and 104.5%.

Recent Trends in Biosensors

NASA Astrophysics Data System (ADS)

Karube, Isao

The determination of organic compounds in foods is very important in food industries. A various compounds are contained in foods, selective determination methods are required for food processing and analysis. Electrochemical monitoring devices (biosensors) employing immobilized biocatalysts such as immobilized enzymes, organelles, microorganisms, and tissue have definite advantages. The enzyme Sensors consisted of immobilized enzymes and electrochemical devices. Enzyme sensors could be used for the determination of sugars, amino acids, organic acids, alcohols, lipids, nucleic acid derivatives, etc.. Furthermore, a multifunctional biosensor for the determination of several compounds has been developed for food processing. On the other hand, microbial sensors consisted of immobilized microorganisms and electrodes have been used for industrial and environmental analysis. Microbial sensors were applied for the determination of sugars, organic acids, alcohols, amino acids, mutagens, me thane, ammonia, and BOD. Furthermore, micro-biosensors using immobilized biocatalysts and ion sensitive field effect transistor or microelectrodes prepared by silicon fabrication technologies have been developed for medical ap. plication and food processing. This review summarizes the design and application of biosensors.

Characterization of dry biopotential electrodes.

PubMed

Xie, Li; Yang, Geng; Xu, Linlin; Seoane, Fernando; Chen, Qiang; Zheng, Lirong

2013-01-01

Driven by the increased interest in wearable long-term healthcare monitoring systems, varieties of dry electrodes are proposed based on different materials with different patterns and structures. Most of the studies reported in the literature focus on proposing new electrodes and comparing its performance with commercial electrodes. Few papers are about detailed comparison among different dry electrodes. In this paper, printed metal-plate electrodes, textile based electrodes, and spiked electrodes are for the first time evaluated and compared under the same experimental setup. The contact impedance and noise characterization are measured. The in-vivo electrocardiogram (ECG) measurement is applied to evaluate the overall performance of different electrodes. Textile electrodes and printed electrodes gain comparable high-quality ECG signals. The ECG signal obtained by spiked electrodes is noisier. However, a clear ECG envelope can be observed and the signal quality can be easily improved by backend signal processing. The features of each type of electrodes are analyzed and the suitable application scenario is addressed.

Mucin and carbon nanotube-based biosensor for detection of glucose in human plasma.

PubMed

Comba, Fausto N; Romero, Marcelo R; Garay, Fernando S; Baruzzi, Ana M

2018-06-01

This work reports an amperometric enzyme-electrode prepared with glucose oxidase, which have been immobilized by a cross-linking step with glutaraldehyde in a mixture containing albumin and a novel carbon nanotubes-mucin composite (CNT-muc). The obtained hydrogel matrix was trapped between two polycarbonate membranes and then fixed at the surface of a Pt working electrode. The developed biosensor was optimized by evaluating different compositions and the analytical properties of an enzymatic matrix with CNT-muc. Then, the performance of the resulting enzymatic matrix was evaluated for direct glucose quantification in human blood plasma. The novel CNT-muc composite provided a sensitivity of 0.44 ± 0.01 mA M -1 and a response time of 28 ± 2 s. These values were respectively 20% higher and 40% shorter than those obtained with a sandwich-type biosensor prepared without CNT. Additionally, CNT-muc based biosensor exhibited more than 3 orders of magnitude of linear dynamic calibration range and a detection limit of 3 μM. The short-term and long-term stabilities of the biosensors were also examined and excellent results were obtained through successive experiments performed within the first 60 days from their preparation. Finally, the storage stability was remarkable during the first 300 days. Copyright © 2018 Elsevier Inc. All rights reserved.